I just don't think that there's some huge media bias against Nintendo
Neither do I. The "press" generally loves Nintendo. It's the games press that's a little iffy about them. If you don't believe me, go back and read stuff most of them (and us) wrote about the Wii. And do the same about the DS. They were both reviled as "gimmicks" and such. Now just think about that for a second. If you were some new gamer, or even a middle-information vet, or a pretty hardcore Nintendo fan, and say, 1up just called the DS "the next Virtual Boy" or the Wii "Phamily Phun Waggle Phests," would you really trust any judgment they pass on DS or Wii games? They've mellowed a bit since then, mainly due to the "don't piss off the majority too much if you don't want your magazine to die" rule, but it's still there, under the surface.
Reviews are very useful when all consoles are similar, like the SNES and Genesis, and the PS2, Xbox, and GC. But since the DS and Wii are so "at odds" with the rest of the industry they are dominating, reviews based on old checklists just don't have as much weight. And I'm not saying that reviewers can't ever gain that trust back, because they had it in 2004 and 2006. They'll just have to work harder to understand what readers expect in a review to make up for the readers they lost when they painted all of them with broad strokes and patronizingly condescended to.
And when there are confirmed stories about review-buying through games like Kane and Lynch, is it possible that this happens with games that maybe deserve high scores? Can we ever really be sure a game got what it deserved? Say what you want about sales numbers, at least they are objective. Now of course I'm not saying sales numbers are the only metric and we should all just scan the charts for quality, but when the game buying populace vehemently disagrees with reviewers, something is amiss and it's not just the "casual gamer" business again.
Reviews in more equivalent times would be a good thing to use. But when the console that is dominating is so "ideologically different" than the console that is losing, it's just hard to believe reviewers are objective, especially when they've previously shown animosity towards one.