I cannot speak for the keepers who use tubs, but I can speak for those who make their own enclosures. I personally feel that snakes in tubs are BORED as hell. They don't get enough exercise nor do they have anything to do.
I make my own enclosures, 36x18x12 for my bps, and if they get over 5 feet they'll be getting larger. I can inspect them without yanking out a drawer, they provide lots of entertainment after lights out as they are always cruising, and I feel they are "happier" in this environment.
There will be those who believe these animals are stupid, instinct-driven creatures, but I don't believe it for an instant. After almost 40 years of keeping herps, and observing and interacting with them, I've learned to respect these animals and to give them OPTIONS.
Unless, of course, you just don't give a crap.
Chris