Look at this in a differant way. Bps dont climb and couldnt care less about having a high ceiling. If you look at the most common size of tank and tubs used if you get rid of the height it only comes down to floor space. The tubs that we use have simular if not more floor space. Tubs just are not as pretty for us to look at but then we dont live in them.

15 gal tank 24 ¼" wide X 12 ½" deep X 12 ¾" high 303 sq in of floor space
25 gal tank 24 ¼" wide X 12 ½" deep X 20 ¾" high 303 sq in of floor space

41 qt tub 34 7/8" wide X 16 5/8" deep X 6 1/8" high 579 sq in of floor space
28 qt tub 23" wide x 16 ¼" deep x 6" high 373 sq in of floor space