I see your point, but only to a point. You are selecting a vacation, where the majority of people enjoying it, are adults, and therefore adult driven, with a few exceptions.
If your ship of choice has a kiddie pool, no one will bat an eyelash, if it is filled with diaper wearing kids, but once you bring a baby into the adult pool, you must realize, you will probably get comments, and possibly be asked to leave the pool. Can you deal with that, and how far will you push it? You want your enjoyment to be the same as everyone else's but, with the health issues already stated, you surely know this is out of most peoples comfort levels, and rightly so, imo....I would also hazzard to guess, that an adult, with adult diapers, would probably not be swimming. I suggested the little pool as a comfortable compromise. Maybe not the fun level you are looking for, but just a heads up to know you may get confronted, by someone feeling as strongly as you do, but on the opposite side of the issue.
All cruisers, in their cruise fare, pay for all the options available for everyone on board, but many don't use all of them. Just because someone can do something, doesn't mean they should. I do hope yourr family enjoys the cruise...I will be on the Epic in Oct, please come back and let us know how things went