The source of the feeling for beauty or balance or "rightness" is hard to determine. My assumption is that in life - and especially in early life as an embryo - there are times when one feels comfortable - and what belongs there is associated with "beautiful." Surely there are more causes, but "pleasant living conditions are beautiful" seems obvious to me.
The small window of the bathroom is sensible as it was designed. That is why "ist" it beautiful. You just have to bring that together internally. ;)