Is reviewability important to videos? Sure, it can be. A lot of my favorite videos are ones that I got really caught up in and would watch a couple times a day. That includes emotional videos and well as flat out entertaining ones. And I really do think it's worth something if you've made a video that someone watches over and over which is why I think it's worth keeping reviewability on the ratings system.
Does it ultimately determine the worth of a video? Of course not. There're plenty of videos that I have great liking for that I don't care to watch very often at all.
But seriously, does it really matter if the ratings system is arguably flawed in relation to how good a video is?
Call me stupid but I am of the opinion that the ratings system is not meant to determine exactly how good a video is. What it's good for is to provide organized thinking about the many aspects of video editing (originality, capture, synch, etc.) so that when we write reviews, our thoughts can be formulated in a comprehensive way.
Is there anyone here who seriously thinks that the top 10% list is a list of the one hundred something best videos on the site? I sure don't. To me, it's a list of good to great videos that can be filtered to specify vids that are good examples of specific qualities. It's a very convenient thing to have around because it points the way to plenty of worthwhile material.
So, what I'm saying is, we're not really doing AMVs a huge disservice by having a disagreeable rating system. Ranked numbers are a stupid way to determine the worth of a video in the first place no matter how we change the categories. So...well, don't take it so damn seriously folks! It's nothing too important, just convenient.

Truth is, we don't have an all powerful categorization of GREATEST VIDEOS EVER. I'd be interested to see some thought put to this sort of thing because I honestly don't know how we can decide what makes the best videos. Individuals have thier own ideas about the issue but there's no overall agreement among us. Not that there ever will be a determined status of greatness among videos (there isn't any such agreement among movie, music or literature critics either).
But I think it would be interesting to see people put more serious thought into what makes a great video because sometimes I feel more meaningful videos are ignored in favor of videos that are simply enjoyable to watch. And I think video editing is respectable enough to praise for something stronger than just well timed editing and impressive effects. I'd like to see people talk more about original or well thought out concepts, high creativity, use of storytelling and emotional strength and depth.
Okay, that's enough of my blabber.