First of all, Reality is Unrealistic. Second of all, stop exaggerating. The answer to everything here, as with everything in DF, is and has always been this - "It's not here, because it's not here yet." Once Toady is bored enough, I'm sure we'll see proper breaching of liquids. With braces, or with demolition charges. We may be able to lower floodgates into water or carve them out of the living rock. The most important thing is that right now, we have the ramping channels. Reverting them to the old way will upset some of the players, even just adding the old channel designation back will upset some people (a minority, I'm sure). The best thing to do now, or in the near future, would be to facilitate the new channels' integration in the game, by removing bugs that negatively affect it and supplementing it with a largely unrealistic, but perfectly-acceptable-as-far-as-the-game-goes ability to remove downward ramps from above regardless of what they're submerged in. This will keep the pro-new crowd pleased, even more so, and reduce the grumpiness of the pro-old crowd to a minimum, getting a net increase in happiness of the community.
1) Don't remove the only way to accomplish something until the new feature that allows it to be done in an alternate way is here, now. (In this case, breaching freezing biome aquifers and leaving clean and safe liquid breaches). Its all well and good to say 'x is coming' (although *you* have no way of knowing, do you?), but the correct approach is to remove the old methods *after* the new methods are available.
1.1) Not everything can or should be added to the game. Old channeling was an acceptable abstraction of wall breaching and climbing/rope use to represent the finished state of the tile.
2) Turn your comment back on itself - the answer to 'unfair' moating is better siege AI. Its coming. By your own logic quickfixes are not the answer, so why do you support this one. (Just pointing out how hypocritical your own logic is, not saying i agree with it since i believe the quickfix doesn't actually fix anything).
3) Upsetting a tiny minority of players is not a reason not to do something, especially since the change is clearly annoying to a large number of players. >60% want the old channeling functionality back in (sum both channeling are good and old channeling is good votes).
4) Both crowds can be satisfied by allowing the new functionality via a different designation. Then nothing is lost. Anyone who gets upset at how *someone else* plays the game should be ignored, and rightfully so. The existence of a designation doesn't make you use it.
5) The bug fixes to poblems created by new channeling are likely to be quite difficult to fix, and might go multiple major versions before a good fix is implemented. Far better and easier to simply revert to the known working version than to wait for all the bugs to be ironed out. I mean, pathfinding is only going to experience more and more bugs - relying on a pathfinding fix is virtually hopeless since it'd probably just get broken every single version.
6) Functionality is key. There are things new channeling cannot accomplish that old channeling could, and that functionality needs to be restored. And there's no single solution to the functionality fix (avoiding miner loss breaching a frozen aquifer will not be solved in the same way as lack of clean liquid breaches).
Your post is basically 'I lost, but suck it up - nothing should be done because its the way it is' with overtones of 'if you don't like to play the game the way i do, the way you're playing is wrong!' That attitude is offensive.