I think removing the all 10s would be quite dramatic - I bet there's a lot of them.
I know that Shameless Rock Video has had some opinions that said things like "I never thought I'd give a video all 10s but with this one I had to".
Whether I agree with them or not there are people who do think it's possible to give a video all 10s.
Also, if you delete the opinion in its entirety, what if it was a really long detailed and useful opinion on all the different elements they liked about the video? That opinion would be lost forever.
In short, although I can understand why you'd want to remove all 10s opinions I dont think they deserve deletion. All 1s opinions rarely offer constructive criticism, so it's less of na issue. All 10s ones can be valid opinions.
Heh, I guess you could just say that, unless the person writes over 100 words on the opinion, an all 10s review doesnt count in the scoring
That would remove many people who dont think about the scoring and just say something is great ^_^