How does cleaning of the heat exchanger work? From my experience with Jaccuzzi-style baths anything that recirculates bathwater gets very nasty very quick and is a nightmare to clean.
That alone probably will make a huge difference in how often you have to deep clean it.
I mean you can as long as you make the bathroom a wet room and shower outside the tub, which is exactly how the Japanese do it.
The biggest issue in the west is the room being wet to start with.
most owned apartments also are not build in a way where it's easy to retrofit. So if you don't do a "in depth" renovation anyway, its often just not a good option from a financial POV. Especially if you have to reroute plumbing (for the floor level wet room sink), especially if beton floor or pre-existing floor heating is involved.