You know people, Weather really isn't that hard to use. And that is why people don't like it, it's "cheap", kinda like paraflinchrachi. What was that about the "Play to win" again? Oh right. We use strategies to WIN. So hey, is Tyranitar really that bad of a Pokémon that you can't afford a spot on a team for it while last gen you were happy to have Heatran, potentially another pokémon for rocks, a spinner and a spin blocker? Come on now. I know you heard it, but this is Gen V. It is different from Gen IV, and I think that is a good thing. Weather just happens to be what Gen V is all about, and it can also make for a very fun metagame, and it also allows some underdogs to shine - Politoed in OU? Who would have thought that last gen, right?
/rant
Ok, you know all that. I don't think that absence of weather "opens up the game", the most it opens up is the skies. If you ban weather, you take away a perfectly viable style of play that is easy to deal with if you know how to play and build teams. Yes teams in Gen V have to be prepared for weather, but do you seriously want to ban something because you don't feel like considering it when building a team?
tl,dr: Banning weather means banning a style of play and won't diversify the game.