How has B/W changed the metagame?

I hate how a lot of people on smogon are trying to ban vulpix and politoed because they affect weather. There excuse - swift swim makes metagame broken. Um yea, thats why you allow tyranitar with excadrill right? >_> Like I said, there trying to create 5th gen metagame rules with 4th gen principles. They really think you can be 'prepared' for everything with one team, but thats not true. You can't handle every strategy with one team, and this is what makes me believe on how some of those people are basing off their 'banning' of certain pokemon.

I haven't played any 5th gen competitive due to losing interest, but Swift Swim is extremely powerful and does deserve looking at. Rain is hands down the best weather in the game. Sandstorm only increases Sp.D for Rock, a generally weak defensive type, and does some minor damage per turn. And yet it's enough to give your team a significant advantage. With Swift Swim, Rain does 3 things for your Pokemon:
1. Double STAB (2.25x) damage on ALL Water attacks, stacks with +Attack bonuses
2. Double Speed stat
3. 100% accuracy Thunder/Hurricane, if you're running it
So it's effectively better than a free Growth and a free Agility. I mean, that's pretty fucking good.