I think it is really a pros versus cons argument.
Reviewing isn't always objective, it is usually subjective when it comes to games. On one end, it may make us frustrated as some games may 'get a free pass', whereas it may seek to validate great gaming experiences that are flawed at times.
For me, it is like comparing Grand Theft Auto IV to Saints Row. One is far more realistic, and technically superior by great lengths. Yet when I walk back from playing both, the technically inferior game is the one I enjoyed more, and would rate higher. Is that fair to do as a reviewer? I am unsure, as I would be conflicted between stating which one is 'better' as better in any art is more subjective than objective.
Now, with something like Mass Effect, from my 5 playthroughs and ~100hrs of gametime, I think that the 90's are fair reviews for the game. Did it have glaring flaws? Absolutely. It had some atrocious issues. Yet despite its flaws, it was one of the best-told stories in gaming history. I craved each codex entry, cared about the great characters, and felt that the last 3 hours of the game (Sovereign's story arc) was bar none, the best event in my ~18 years of playing games.
So did that rescue the technical mess of Mass Effect? For me it did. Subjectively, technical aspects of a game are far lower on the totem pole than the story and lore of a title, and the gameplay qualities I enjoy (mainly RPG or simulation management).
I could list a lot of games I play that have those qualities. Deadly Premonition is a great example. Despite the horrid reviews by IGN and others, there is a growing cult following for the game's well-told story and hilariously quirky characters. Is the DP cult objective? No. But subjectively, there are a lot that enjoy the game, despite the objective flaws.
To summarize, any art form is subjective. You may not think The Dark Knight or the Mona Lisa are the best ever, but for my tastes, they were. That is why aggregates exist. That is why there are 100's of review sites. You may feel Mass Effect was overrated, but for me, it was one of the top 5 games I've played in my life. Those views eventually balance themselves out. Even then, our subjective opinions may differ even from the aggregates - parts of me think ME1 was superior to ME2, despite reviewers feeling much different.
*edit*
And for the record, I'm in total agreement with you as to befuddlement as to why Deadly Premonition got a 2.0 from IGN and a 4.1 from our very own VGC. The game rates far higher on the list for me, as it does for user aggregates. From a technical standpoint, DP is incredibly solid. No frame skips, short loading times, no pop-in, ect. All packed with a phenomenal story and a lot of 'fun'. Having played a lot of turds, I'd think I would have a crap dectector after buying Two Worlds, and DP is nothing short of cult-favorite excellence. Subjectively, though, I guess some people don't appreciate the goofiness of Deadly Premonition. However, I don't understand why they wouldn't appreciate it, and rate it low, when other games like Obscure got higher reviews....I own a large number of survival horror games from the PS2 onward, and DP is nowhere near the bottom, despite it being quite low on the review lists.