Basically, you don't get a second chance to make a first impression. No matter how good the game gets, they won't get another opportunity to give me the experience of newly discovering D3 with my friends.
The game now is better than it was at launch. With 1.05, the game will finally get reasonably close to the point where it can be considered on par for a Blizzard product. The shitty part about that is that it means the game was markedly worse at launch than it should have been.