Extensive talent tree changes coming in Cataclysm.
I'm not really sure what to think of these changes. In general, I like the smaller trees. I'm just not sure about the forced specialization.
It means that there is much less potential builds out there. No 30/11, or 21/20 builds will be possible. But on the other hand, such builds tend to be rare anyways. Sometimes choice is an illusion, and in reality there are only a handful of viable builds. So the end result might be the same now and in Cataclysm, but it will just be more obvious.
As well, right now the 11 and 21 point talents tend to be a little weak, just to keep other-spec builds in check. This is especially true when leveling. Take paladin trees for example. Aura Mastery, Divine Favor, Divine Sacrifice, Blessing of Sacrifice, and Sanctified Retribution are good abilities, but they are a little boring.
Compare them to the 31 point talents of Holy Shock, Holy Shield, and Repentance. Those talents are "fun" talents, but they come so late, and you get them at a much higher level, just to prevent off-talent builds from picking them up. Wouldn't Protection leveling be much more fun if you could get Holy Shield at level 20?
The one "fun" early ability, Seal of Command, is perfect to get at level 20. Unfortunately, it's quite arguable that Seal of Command has made Protection overpowered at producing AoE threat. Because it is available so early, Protection can pick up Seal of Command, forcing a choice between leaving Protection slightly overpowered, or weakening Retribution.
The enforced specialization does away with those concerns. You could move more interesting abilities earlier in the tree, confident that you won't accidentally overpower one of the other two trees.
The current trees are a little top-heavy. Sometimes it's hard to be enthusiastic about pushing through those rather boring mid-tier talents, and then you want to get all the juicy, game-changing top-tier talents.
It probably will be easier to balance PvP as well. PvP builds often forwent the deep damage increasing talents in favor of mid-tier utility and survival talents.
So on the whole it's probably a good change that strengthens the game mechanically. I guess I mourn the illusion of a potential vast amount of builds. An mirage of possibilities. But that was just a dream, and high-end group play rudely awakens you to the fact that only a few builds are ever truly viable.