As long as they can keep them filled correctly and cleanly. I was at a Holiday Inn once that had pumps for shower gel, shampoo, and conditioner, but the shampoo container was filled with shower gel...was not my favorite experience.
I'll admit that I'm someone who has amassed a bit of a personal stash (really useful for guests, trips where I'm not staying at a hotel, and so on). So part of me is sad to see them gone for those reasons. But I think the environmental outcomes are good (and good for Marriott's finances as well). Theoretically, I suppose there's isn't anything to stop someone from buying refillable 3 oz. containers and filling them up from the pumps though...