I could tell you why, but then I'd be banned. But seriously, these reviewers either a.) have crappy equipment or b.) can't easily catch image deficiencies without doing proper image examination on a computer (which they should in that case).
Of course there are those of us who do see these deficiencies without having to actually view the image closely on a computer, but none of us are doing these reviews.
Now, these various reviewers have many reasons for not seeing these deficiencies in image quality, and many make excuses. Some say the deficiencies don't matter when viewed on their equipment, which typically ranges from low res or smaller monitors. These people can't be bothered to examine the image correctly and provide useful advice for those of us with projectors or a discerning eye, so they just say "good enough" and move on to the next review. Of course these reviewers may be pissed when in the future they get some nice equipment, they find that many of their favorite movies are lacking in quality, oops guess you should've been on the studio's butt about the issues instead of glossing over them due to low-end equipment.
There are those reviewers who do have the right equipment, but I can't think of a single one that can actually spot dnr, or artifacts on their system unless the dnr is major. We've seen this in the past, they talk up a new release, and when Xylon shows us the truth, they say they didn't spot it when watching the movie and that it's "not a big deal."
I do feel that reviewers need to take the video rating seriously, and do whatever it takes to give us a true review of the quality. Not how it looked when viewed on a neighbor's 20" set from 30 feet away, not an opinion but the facts. We need proper reviews so that the studios know when they're going too far, and so that any of you without good equipment now won't be punished when you finally do get that brand new 150" home theater. We're all here because we love movies and we want to see the movie in the best way possible, these reviewers who don't take video quality seriously are hurting us all. Even if they love dnr, or whatever, the point is they need to tell us the truth about the image so we can make the decision, why do we always have to wait for Xylon to show us what the studio's have done to an image? Step up to the plate reviewers!