Your right in saying that without its weather abilities, Politoed would be very outclassed in the OU metagame. But similarly, even Tyranitar would see little use because its typing and low speed would hold it back without the boost to SpD in sandstorm. It would face a similar fate to Metagross. Of the five weather inducers, I think Hippowdon is the least reliant on its respective weather and would have the best chance of staying OU viable if it didn't have Sand Stream. The mere fact that it packs Drizzle makes it not only viable in OU, but one of the most influential pokemon, if not the most. ... Politoed has one of the most powerful moves in OU and it gets the boost just by switching in. So while I agree that Politoed would be outclassed if it didn't have Drizzle, or if any other pokemon you mentioned had access to Drizzle same as Politoed. But Politoed deserves the respect it gets because it is still a viciously powerful pokemon.
Well, that's pretty much exactly what I was arguing against. With Sand Stream, Tyranitar is not outclassed as a Pursuit trapper by any pokemon, due to its STAB and enormous SpDef and Atk. It's its own ability that allows it to be a superior pokemon in itself; we're not talking Unnerve Ttar or Damp Toed.
But let's say you're against a Drizzle team. Politoed is the least powerful viable Specs Hydro Pump spammer that could possibly be on that team. Keldeo and friends get the benefit of rain in this judgement because Politoed itself is only ever used on rain teams (I understand this is a tautology, but that's the point). Therefore, Politoed's Drizzle provides no advantage to itself enough to merit the use of offensive Toed over another similar pokemon. Politoed's relative worth lies only in its team support; the rest is necessary filler.
I hope that made sense, nmitchell and yee. The only reason to justify Politoed is the team support it gives; even with Drizzle it has nothing to justify itself as a good pokemon, in opposition to Tyranitar. Drizzle is just that bro-...good, that it makes Specs Politoed into a top-tier threat and many things more powerful or effective into potential ubers.
Having said that, I do believe non-weather can be viable, even more so now big bird is on the way out. Deo-D offense is obviously very effective as has been established already, but stall, semistall and balance are somewhat more difficult. My most successful team this gen has been weatherless defensive balance, although it took a hit with the BW2 releases of Torn-T, Lando-T and unbanning of Garchomp. I've found SpD Celebi, RestTalk Gyarados, fast Jellicent, and Latias (surprise surprise) to be very anti-weather on the defensive front.
I'd love to know if anyone has achieved the holy grail of successful weatherless BW2/Torn-T era full stall though!