Balance is simply not part of the game yet. At all.
It's silly to talk about balance for dwarves when we haven't even gotten the complete the army arc yet, or more detailed behavior for megabeasts, or magic (which, recall, dwarves will usually be on the receiving end of.) Those are the things dwarves need to be balanced against.
Imagine if Toady had wasted time balancing the 2d version (as many people in the forum suggested back then.) It would have all gone to waste, since things changed so completely. The game still isn't done in several vital ways, so it can still change and negate any balance suggestions we're making here... balance should simply not be a consideration except in the most absolutely broad areas (e.g. "don't give dwarves the ability to shoot lasers from their eyes.")
Even aside from that, though, I strongly and completely disagree with all the suggestions made here. Contrary to what is suggested, I do not think these things would actually make the game harder, overall; in fact, the importance of 'high-value' dwarves is what lends much of the game's difficulty right now. Whether they use super-dwarves or not, fortresses rarely die to external attackers (I almost never depend on my dwarves to fight); but they do fall apart when a high-value dwarf cracks.
The game is all about epic works of art and legendary warriors. It's central to what Dwarf Fortress is. I would say that having legendary dwarves in the game world (people who can accomplish great things and, conversely, destroy your whole fortress in a tantrum) is, in fact, more important than having a balanced game, because without them it just isn't Dwarf Fortress anymore.
(I also think that the original post completely misses what is unbalancing about the game at the moment. The strength of individual dwarves isn't a big deal; the ease with which food can be produced and enemy forces totally negated by fortress design are big balance issues. I simply do not see the points this thread is focusing on as being major balance concerns compared to food, fortress design, and things like that.)
[ May 30, 2008: Message edited by: Aquillion ]