The point is to "annoy" players, as you put it. It's actually called disencouraging. When you know you'll have to perform extra actions, you'll think a little before starting your construction.
The magnitude of the change does not "disencourage" anyone from doing it. It just becomes more annoying to do for no reason.
Well, if it's annoying you, why don't you stop using it? That's the kinda logic that goes into the thing. It becomes more tedious, therefore more difficult. If you search your memory for the origin of the current "batch build walls" feature, it was because building walls individually WAS too tedious. We didn't get a net decrease in anything but player actions with that feature, and I don't think you'll disagree that it was an improvement.
As to why player actions are a resource... well, put it this way. The time it takes to designate something is irrelevant because of the pause feature. The time it takes to actually dig the thing out is also irrelevant because you normally have quite a lot of time on your hands.
The amount of time you have before an attack is not infinite, unless you have decided to turn off invasions in the init. You still have to decide if it would be a better use of dwarven time and labour to dig the great outdoor moat and seize a section of the underground for your use, or dig a much cheaper in terms of time hole at the front of your fort and sticking a retractable bridge over it (Which, if long enough, can then be upgraded, in complete safety, into a pretty broken siege killing deathtrap that also gets rid of those pesky elves) Your comparison between the two fails.
Not only that, I also failed to see what you tried to counter here. I didn't say "infinite", I said "quite a lot". The practical upshot of "quite a lot" is that to shift the balance in any meaningful way, the time to dig out a "full" channel would have to be disproportionately greater than that of all other mining activities. The fact that you can still seal your fortress in with a small moat and little effort is ever so slightly offset by the fact that if there's ever danger outside the fort, you're stuck with just the stuff you had the time to haul in. Yes, it's perfectly feasible to live completely underground, what with underground forests and all, but this cuts you off from overground plants, watersources and trading, not to mention it makes all of your populace cave-adapted. I don't think much thought went into balancing yet, but as a whole, the system isn't too unbalanced.
The resource cost for a channel is usually negative, because you get rock from channelling (unless on soil, in which case it's zero). Therefore, there's only one way to apply balance to channels - make the player pay more of his attention. Micromanage, essentially. That's also a form of balancing.
Digging tunnels is also an activity that has a "negative cost" as you define it. How do you propose we "balance" that? (In the sake of being fair, of course.)
Why balance it? Digging isn't a negative-cost activity for no reason, that's your sole source of any sort of resources bar wood. Channeling is a subset of digging, of course, but I didn't say its negative cost is a bad thing. Unlike plain channels, plain tunnels cannot be used as a defence though, much less an impenetrable defence, so... yeah.
Now, when your first-pass channel is done, (I'm presuming here the re-channel functionality is added) you will have to look away from anything else you might be doing and designate the ramps for removal. The pause feature lessens the magnitude of the impact this has, but it's still there nonetheless. It doesn't really have to be a limited commodity in order to be a resource.
Simply making something more annoying to do only serves to drive off players. Since the goal was to weaken channels as a defense, and that goal has demonstrably not been met (Since people can simply clean them and go), that is all it does. Except result in dwarven deaths from a dozen other things like channeling the ground out from under their feet and falling into the underground, or channeling into magma and then going for a swim on his way to the food stockpile while other dwarves compliment him on his !!Pig tail trousers!!
What you described are mere bugs. They always happened before. The fixes for a lot of those bugs are rather straightforward, so if you bring the bugs themselves to Toady's attention, they may get fixed. Especially if they are so irritating. Ramped channels aren't a bug, even though they're on the Tracker, however I didn't yet see the "dwarf paths into magma after channelling" or "dwarf falls to his death after channelling" bugs in there, for some reason.
Oh, and "don't use it if you don't like it" is a bad argument. It's like saying "don't use overpowered units if you don't like them" in any RTS. The problem is that they're there, and while DF isn't a game with real competitive play, it's generally a good idea to make the game difficult on its own rather than have the players devise self-imposed challenges.
The problem here is that there are varying degrees of skill between players. What would be a challenge to you or I would completely crush anyone trying to pick up the game. Given how steep the learning curve is already, I don't think that's a good idea. If you want a greater challenge, mod your goblins to be size 50 (And give them buildingdestroyer:2) and downgrade dragons from megabeast to wild animal status, and have them hunt in packs of 30 like I do. Or give your carp the ability to breathe fire (That makes fishing very Fun).
Given the multitude of alternative routes for sealing off your fort that you and other pro-old people here have brought forth, I don't think you can use the "new players will get crushed by sieges" argument here. Making a single channel as a defence is cheap even for new players. And as I said, I don't really like self-imposed challenges. (Though I like modding - go figure)
The Overpowered units in an RTS game analogy you present is also a false one. You are good at making them it seems. In an RTS game, if you don't use them, you'll likely lose, because the enemy has no such qualms. In this invaders do not use "overpowered" units. If you want overpowered, magma drowning chambers are pretty unsurvivable and unbeatable. Does that mean that, following your own logic, we should no longer be able to build them? What about collapse traps? They are even more dangerous than a magma trap. Does the same hold true for pit traps, where you pull the bridge out from under the siege force and cackle as they fall down a deep hole and splatter? How about weapon traps, or cage traps? Both are very effective means of defenses, especially since you just stick them in a bottleneck and shred the goblins before they can harm you. Loading them with green glass trap components made at a magma glass furnace has no cost at all.
Some good points here, but still. What you describe are in many cases rather elaborate constructions that are, well,
supposed to, even
designed to be impenetrable, by you yourself. Trapped hallways and magma-flooding corridors are a great defence, unbeatable by the average goblin army, but think about how much of your effort will go into them. For the very cheap hallway of glass traps, you still have to make a magma furnace, which implies handling magma and its inherent dangers; you have to set up a glass component production line, churn out quality mechanisms, then designate each and every trap individually and wait until your mechanics brigade hauls the hundreds of components together and installs them (this is imagining a three-wide, six-long hallway filled with 10-component traps). However cheap it may be for your fort, you still have had to make the effort to do it, and there's no need to balance that.
"Overpowered" defenses have their place helping newer players deal with sieges and the like. We can afford to be more creative, and we are. I don't use channels for defense. I rely on malevolent architecture.
Good for you. Personally, I always did. Now I usually make walls with guard posts as the initial line of defence. I don't want to muck around with channel defences as they are now, since walls don't require quite that much effort now that they're batch-built, and also shield from arrows. And channelling has become my most-used tool on par with digging, while my usage of stairs has dropped to miniscule levels. I think the new channels are a great replacement. They'll be even better once all Required Secondary Features and Bugfixes are added.
I also find it curious nobody commented on the fact that I'm not, in principle, against the old channel system.
And, Squirrelloid. I can't help but notice:
You might almost have a point if hundreds of thousands of designations per dwarf year wasn't typical. The extra inconvenience is unnoticeable. Lets be honest, there's no way to make building a simple moat a project because its just a small thing next to crazy pumped maga traps and 20000 block castles.
If it's unnoticable, why do people keep noticing it so much?