I suggest posting this in Bathrooms.

Bathrooms, Toilet rooms and laundry rooms shall have a ceiling height of not less than 6'8" Exceptions: 1. For rooms with sloped ceilings, the required floor area of the room shall have a ceiling height of not less than 5' and not less than 50% of the required floor area shall have a ceiling height of not less than 7' 2. The ceiling height above the bathroom and toilet room fixtures shall be such that the fixture is capable of being used for its intended purpose. A shower or tub equipped with a showerhead shall have a ceiling height of not less than 6'8" above an area of not less than 30X30" at the showerhead.

Well it'd be a big deal to me. I use my tub every day. If I check into a hotel -I ask for a room with a tub. That's how important it is to me. Then again, if it's a pretty free standing thing that wouldn't cut if for me. Has to be safe. I'd have a problem with a free-standing. Having said that-the house we bought didn't have a tub in the master, just a tiny shower, and we still bought it. (Then we remodeled, which is a whole another long story. No, it wasn't smart financial decision) We do have a big shower in master bath too now,. i use it as well, but on some days I'm really restricted to the tub. We built it all in a way so it's most safe to use for me. Frankly I cared less about future buyers. So you might stumble upon somebody like me, Or you might not. Or who knows. Now, absolutely no tub anywhere in the house..that'd be a problem. Maybe not for all, but for many. There are times when a tub can come very handy.

Smaller windows above the water line,and a big shower. I have a 4 1/2 x 10 shower and I thought it was ridiculous (and to some it is) but I really like having my own area. .We have shower heads on each end with a rain head in the middle. If anything were to happen, it easily would accomodate a shower chair or an extra person if need be. We are in Florida so temperature and being chilly isnt a concern. I wouldnt dissuade you from building a big shower. You have to weigh whats important to you. I had the same size shower as you have in my last home, the larger shower is a game changer.