we've recently replaced a 15-year-old bath. New one was bought online, so we couldn't sit in it, but it would never have occurred to me we might need to! (Didn't sit in old one before buying either - a bath's a bath, I thought)
New bath is, I reckon, 3-4" shallower than old bath - it's both lower, & on higher feet. we are all disappointed - you just can't wallow in this new one 
granted it will save a lot of hot water & bathroom hogging but is this a thing now (to save water maybe?)