I agree that this is a good thing.
When a developer rushed a game just because the publisher demands it, it ends up being rubbish. Or at least, the developer is forced to only focus on some stuff before release, rather than polish the entire game. If Blizzard feels that Diablo III needs more time isn't it logical to give them that time rather forcing them to release an unfinished product? I for one want to get my moneys worth, and if that means waiting a bit longer I'll gladly do it.