The thing is, basing OU / UU / RU / NU off of usage is how we perceive their power. If a Pokemon is used a lot it's obviously bound to be pretty powerful.
Any way of tiering is bound to have its flaws, but we've found usage statistics to be the most accurate way of deciding where a Pokemon should be ranked.
Banning nothing and ranking Pokemon by base stats won't make for a more balanced metagame, OU will still play exactly the same whether we call Pikachu OU and Thundurus NU. The Pokemon are used a lot because of their niche in the metagame, not because we've deemed them OU and therefore the only usable Pokemon.
[12:59pm] CDXCIV: Hugendugen said 12 hours ago in #x: Don't stooooooooooop thinking about tomorrow
[12:59pm] CDXCIV: mikel said 12 hours ago in #x: DON'T STOOOOOOOOOOOOOOOOOOP BELIEVIN'
[12:59pm] CDXCIV: Hugendugen said 12 hours ago in #x: stooooooooooooooooop and stare
[12:59pm] CDXCIV: Hugendugen said 12 hours ago in #x: I think I'm moving but I go nowhere