Boy, there's a lot of unecessary flaming here. All I wanted to say is that according to some studies we were shown in one of my software development classes, there's a definite limit on how fast you can develop software, and it depends more on the programmers than on the tools they use.
That's not to say XNA is a bad idea...I don't know, I'm not a MS fan, so I'm automatically anti-XNA, but I don't think this will have a huge impact on development times or quality. Actually, I think games have already hit a pretty high point in quality. Nowdays when a game sucks it's usually because the concept is boring or the gameplay is generic, not because it is truly unplayably bad like many old SNES and NES games.