Wait, we're complaining about a nonsexual act involving the exposure of a woman's breast? Prude Americans (yes I am an American also).
Complaining about the diaper change is completely acceptable. It's not proper to do so. If the bathroom doesn't have a fold down for it don't most parents these days have those foam flaps to put a kid on? From my friends that have kids they can change a kid in under 60 seconds. Hell I even have done it a few times and didn't make a mess. I did walk out of the bathroom looking like I had been hanging out with Pablo Escobar (the baby powder) but it can be done in a confined space safely and cleanly.