There's one big factor that hasn't been mentioned about large tanks: They're too TALL. I had a 55gal for my beardie, and I would never get one again...even for a big lizard. 55's and anything above them, unless custom made, are usually way too tall for ground dwelling snakes like BPs. The extra height makes it twice as hard to keep temperatures where they should be, so most people use lights to boost the temps which drains humidity dry. They're just too much trouble...at least for a Ball Python.

Now, a divided large tank for corns or other climbing low-humidity snakes is another thing entirely...