But if you're relying on your console being a solid default favorite platform for games because it makes financial sense there's nothing wrong with that. It may not be as satisfying a "win" as exclusivity, but it's precisely the sort of win that you want. And it should still be flattering that developers are targeting your console merely because they think it's a good system rather than out of any backroom dealings.
Of course, you can change the equation with custom hardware, as the Kinect has done, and that has generated a few decent exclusive titles. We'll see what MS does with the hardware with the next console rev, maybe they'll be able to deliver more on the promise of the hardware and bring more major developer attention than it's gotten so far.
But I also think that a thriving indie dev culture, as the OP is calling for (or rather, chastising MS for thwarting) can do the same thing: it can give a platform exclusive titles (games, but the same could be said of non-game apps) at least for a while, just because small indie devs can often only target one platform, at least until their indie title is a hit bringing in the cash to target other platforms.
(Had a little bit more but will have to leave it there as my laptop's reserve battery power warning is getting very insistent.)