I dunno, I mean, the problem is, if someone is attracted to XBLA's distribution system it's going to be by and large because they don't have any money, they are a bedroom programmer and are either a one man operation like Kayin, Zara, Me, etc, or perhaps up to a three person operation where each person can't commit to even close to full time.
Now when you are a one man operation like this and you are making your first game, you want to make a smaller game that just does a simple concept well. Making a studio level game would just take way to godamn long or would end up being shit despite its depth. So you make a simpler game and it sells and you keep making XBLA games, or it doesn't and you give up on the avenue.
The chances of making enough money to go "Cool, I should actually invest in myself and get a bigger team together here and start making something really substancial" are pretty rare and pretty scary especially when all you have proven is that you can make a smaller game competently.
People only have so much time in a day, and some of that time HAS to be spent doing something that is actually going to feed and clothe them.
It's really easy to claim that people should be making these crazy good games. But why should anyone do it? Failure is too scary to indies, and the amount of work required doesn't seem worth it to a major studio.
It's never going to happen unless some indie makes a game that is ALMOST big, that does really well in sales, then you might see something a little more ambitious. Take the Castle Crashers guys for instance. But the chances of them just selling it through more traditional chanels is very high because major publishers aren't stupid, if someone has a real chance to make a game like this, they will want a piece of the action and will get involved.