While it's true that it may be "less viable" in a sense, I would not say that it is not viable, either. Trick room took a turn to set up, and yet was still a very popular and successful team in VGC 10. While you can argue that weather matters less than completely changing the speed ordering, I think that you can't discredit weather simply on the grounds that it takes a turn to set up and isn't unlimited now, despite those certainly being disadvantages. On the bright side, though, it encourages intelligent choice in who is your weather pokemon instead of limiting it down to tar, obama, kyogre or groudon, possibly leading to more team cohesion. Add in that the opponent doesn't get instant weather either, and it's more likely that the weather effect that you want to be up will stay up.