As a fellow cruise fanatic who (I think...) is a bit older than you are, I am disappointed (but not surprised) to hear this.
I am one of the truly lousy sleepers out there so travel with ear plugs (useless) and sleeping pills (addictive but.....).
I am increasingly reading reviews of new ships with some amazing noise issues - while I'm not an engineer, I guess it's related to how the actual cabins are inserted, attached and insulated to the hull.
If you want a laugh, do a Google search on Celebrity Beyond Noise and watch the YouTube videos .... it literally sounds like the cabin is being attacked by a rabid posse of squirrels and (do they get rabies?) woodpeckers!
Thanks again for you much appreciated and excellent review!