I think the may problem people have with it (now that we're all happy that trading is going to improve somewhat) is that it's, well, not dwarfy.
Dwarfiness is having entire rooms full of gems and precious metals, checkering your floor with gold and silver tiles and still having enough for each person to have their own personal money bath. Now you... can't do that.
Let me put it this way. You think Erebor got all their riches from Dale, or the Iron Hills, or Mirkwood? Hell no, they mined that stuff themselves!
I'm not sure what you mean, who/what's Erebor?
Are you really sure you know that it's going to be completely impossible to do things like that in the future, though?
For starters, keep in mind that the 31.01 absurd overabundance of metals was a very temporary fluke that existed for about 10 months until Toady was done fixing all the bugs introduced in 31.01, and could start working on the actual game functions again, and the absurd overabundance was the first thing to go. That kind of mineral abundance was never intended for the game. 40d had much less material. Now, that said, I still think the current method is far too barren, and hope things will move back more towards 40d's mineral concentrations, even if not all the way there, but closer to 40d than it is now.
Undergrotto was in 40d, and managed to make a huge palace of solid precious metals like gold and platinum. Retro did that by trading a few blocks of ore and bars of metal at a time over the course of about 10 game years. A whole palace paved in gold. Trading. Back when you aren't even supposed to trade for things you need.
Maybe you could have a little more faith in Toady being willing to cater to multiple types of playstyles?
(If trading for gold is somehow not enough for you for whatever odd reason, in which case, what you seem to be demanding is that the game never change at all from what you have in 31.18, then there's still that init option Toady is going to leave behind to ensure that when you flick that switch, the game never changes at all from what it was in 31.18. Isn't that exactly what you want?)
I don't think dwarves should ever have access to magic, apart from with artifacts, and maybe alchemy or exploiting components that are for whatever reason naturally magical. For example, nether caps could be considered naturally magical, or dragon skin, or whatever.
Dwarves are clearly the best race when it comes to crafts and the mundane, nobody else should be able to compete with them. Other races should have magic in keeping with their theme, to make up for what they can't do but dwarves can. Obviously elves have some abilities to extract wood from trees without chopping them down, and they probably should have magic that lets them control animals and grow trees into the shape they want so they can live in them. So they should probably have an array of druid powers.
Humans are basically the same as dwarves, but they can't do what dwarves can do, and should have a very hard time mining otherwise why wouldn't they just live underground? To compensate, they should be able to use some magic, I'm thinking wizard magic or priest magic, so they can heal people and fight better. (They don't have the benefit of being totally enclosed most of the time, so they need to be able to fend off aerial attackers better. Also it makes sense, since they're bigger and have longer limbs that can apply force more easily).
Kobolds are adept sneakers and thieves, I guess they don't really need magic powers.
Goblins, I don't know if they need magic powers. They should be able to survive by pillaging, as opposed to thieving.
There's no particular reason why magic needs to be obvious and showy. Anything that does exist in a fantasy world that can't exist in ours can be considered magical. For example, the wealth of life in caverns must be magical somehow. Adamantine and slade are probably magical. Dwarves must be sustained by some kind of magic if they can tolerate wandering around near lava. Kobolds' ability to sneak so well might well be a subtle form of magic, like LOTR hobbits and their ability to sneak.
Thing is, putting in magic for elves to use is the same thing as putting magic into the game... it's just turned off for dwarves in vanilla, but eventually even vanilla is expected to let you play as elves, once they are given a chance to be sufficiently different enough that they aren't just dwarves with some of their features turned off (like, say, giving elves magic to differentiate them).
Even if dwarves don't get it, it still has to go into the game to give it to anyone.
That means the magic-happy people can go play Wizard Tower (old dev goal) instead of Dwarf Fortress. Flavor-wise you still have no dwarven wizards and only humans and elves and demons and maybe goblins are the "wizard" types, which seems to be what you want, and what the pro-more-useful-magic people want.
The only thing I worry about with magic is just in how random it really is. I remember one of the magic suggestion threads having dwarven wizards that are completely uncontrollable who do nothing positive, but can randomly open up a portal to the HFS inside your fortress, because having a 10% chance of completely destroying your fort every season for utterly no reason was "Fun". That's the sort of magic where the only answer is to shove anyone who shows any magical talent into a volcano on sight. (Fortunately, Toady certainly seems to understand this part.) I can certainly understand why people say a magic system where someone is a "firebolt mage" who has "cast firebolt" at legendary and does nothing but spit firebolts is boring and shouldn't go in, but that doesn't mean the opposite extreme, where the game just rolls a die every season and suddenly declares your fortress crumbles and there's nothing you can do about it is a better answer at all.