This is a big reason why I miss the old GIA site. Their reviews were pretty much the only ones I cared about because they approached them with intelligence, and the mission statement of the site as a whole (even if it was never stated explicitly) was to elevate the discussion about games and gaming in general.
You made an excellent point about nuance. This is part of why I found the reaction to IGN's Killzone review so funny. They gave it a 7.5, which is still a very respectable rating. It's not like they gave it a 1 or anything. But anything less than a 10 was seen as unacceptable to them. It's what I like to call the fanboy mentality; go on any site that accepts user-reviews of games (Gamespot, Gamefaqs, etc.) and upwards of 90% of the ratings are at either extreme: 10s, or 1s. For the same game. If no numerical value is attached to the review it falls in to the "sucks" or "rocks" categories.
For instance, the Tomb Raider sequels got lukewarm and sometimes outright hostile reviews from a lot of people, and probably the number one reason was because they were seen as being too formulaic (I include in this complaints about the game "engine" being outdated). As a Tomb Raider fan, this didn't bother me...I LIKED the formula. So I took the complaints in stride and just enjoyed the games (well, except Angel of Darkness...what a wasted opportunity that one was). OTOH, I hate the Dragon Quest games because they are forumlaic and boring. Go figure. "Formulaic" in that case is a bad thing, because I don't like that particular formula. Lots of people do, more power to them. No one can be perfectly objective about everything; when I "review" games on my LJ, they are not so much reviews, but stream-of-consciousness type of things. I don't even pretend to be objective about, say, Final Fantasy. I don't think objectivity among reviewers is the problem so much as transparency is. If someone doesn't like a particular genre and is forced to review a game from that genre, I think he/she owes the reader a bit of disclosure up front so they can contextualize the review better. Not that you can't do that without disclosure; I've read enough RPG reviews (particularly reviews of Japanese RPGs) in my time to know when I can merely take one with a huge grain of salt, or just dismiss it out of hand. (Clue #1 is when they complain about there being "too much talking" in the game).
I think gaming journalism as a whole is in trouble, and the problems with game reviews are just symptomatic of a deeper problem.
This is a really phenomenal roundtable discussion that pretty much goes into a lot of what we've been talking about.
What really bothers me though is the scary number of people who won't even try a game because "so-and-so said it sucked". It's almost as if we've forgotten that, well, the whole point of this hobby is to have fun. People really do lack critical thinking skills; it seems that with certain games, once the talking points are out there, that's it. That's why I played Xenogears in its entirety at least one time despite having misgivings about it. Too often I find myself arguing with people who can't debate the merits of a particular game beyond the popular talking points (Final Fantasy 8, anyone? "Squall's an asshole." "Did you play through to Disc 3?" "Uh, no." "Come back after you have, and then tell me he's an asshole.").