Interesting - even I have to admit it is hard not to comment in a way that might sound like I am criticizing you, so please let note this is not directed at you.
A cruise ship should be designed intelligently enough that treadmills would not echo through the ceiling. I am glad you got your compensation. I do think they were pretty fair with their considering you had a beautiful suite. I guess they just bet that most people will not complain about what are obvious problems.
As far as the treadmills go, I am guessing someone from passenger services put them up, then at some point some know-it-all passenger saw perfectly good treadmills and took the sign down. Then the next shift of gym attendees came on =and they really didn't know about it.
Just a thought.