Here is something (or something else, depending on your point of view) that World of Warcraft ought to copy from Warhammer Online.
I hate that, in the talents window, that spending a talent point is complete and final the moment you click on it.
There are no “take backs,” you’re done and if you made an error, you have to go spend some gold to fix it.
In Warhammer Online, the equivalent window has a save button at the bottom, and no change you make is committed until you click that button.
Of course, I did not actually click that button in Warhammer Online the first few times, having been trained by the WoW’s talents window (and EverQuest II’s alternate advancement window, which behaves the same way), but once I figured out why my selections were not sticking, I saw the advantage of Mythic’s method.
Now maybe I am the only person to mis-spend a talent point now and again, but short of Blizzard giving us multiple talent profiles, some way to alter or confirm your selections before you commit them is a change I would like to see.