I don't think it would be a good idea to force everybody to carry a weather inducer. Some people just plain don't like using weather, so if everyone just tosses Gliscor and Azumarill onto their teams, and uses the last 4 slots to continue with whatever strategy, then the loss of other weathers would actually make Sand more neutered than dominant. Besides, by bringing back Excadrill, there is a lt of incentive to run Sand, as there wont be Politoed/ Ninetales to shit it down. The potential for non weather vs non weather is just an "oh well, its now a normal BW OU battle" moment.