I saw we either:
'Allow' every NFE Pokemon, then ban a few odd ones that would break the metagame, such as Porygon 2, Chansey, Rhydon etc.
Or we ban all of them. All this second option means is that things like Trapinch and Vigaroth would see no use. Things like Pikachu, Scyther, Rhydon, Porygon 2 etc are actually all viable in OU/BL and would thus still be used.
EDIT: The only final option would be to allow everything (except for the obvious bans stated above) that was fully evolved in a previous generation. This includes stuff like Gligar, Electabuzz, Magmar, Tangela et al being playable in UU. This could get very nitty-gritty though, as some people would want to ban OU-lites (see:Gligar), but allow Pokemon with big differences, such as Electabuzz or Scyther. Where would the line be drawn?
See, I would disagree with all three of those.
Why should we move away from the generally recognized rule of: NFEs are all banned unless they serve a different purpose than their evolved forms? That is the question that needs to be answered by anyone arguing for other methods of sorting.