I prefer cages. I like giving the snake as much room as reasonably possible and giving them the ability to have a better light cycle and window to the world. Do they need it? No. It makes me feel better doing it though. I also enjoy being able to go in and check on them without having to pull out tubs.
All that said I do have a rack but I have always used it for young snakes until they need a larger cage. Right now my young Kings and Mad Hoggy are in it waiting on their cages to be delivered.
My rack is from Animal Plastic and is the eco model meaning the sides and back are mostly open. I went with this to give them more light and I didn't have to worry about keeping heat as it is in my heated snake room.
For me racks have a place but they are not my choice for long term keeping. My snakes are pets though and I certainly understand a breeder using racks and I would too if I was one.