As I am in my mid 60s I very much echo your sentiments! On my table two tablemates (out of six) were in their 90s. One other went to bed after (first sitting) dinner, another went after the show. We all commented on the number of wheelchairs, rollators and walking sticks on this cruise compared to previous cruises on Aurora. So maybe not surprising that the Silent Disco was empty, on my previous Aurora Cruise it had been packed. Granted, that was during school holidays and had a cohort of school employees wishing a child free break.
There are signs that Aurora is being "neglected". Games equipment not being replaced when necessary. No recognisable guest entertainers (though the ones we had were excellent), despite them being on the other ships etc.
I have two more cruises booked on Aurora and tbh I doubt I'll be booking any more. I have realised that I sailed on Aurora a lot because of the length of cruises (to me the distance I need to travel to Southampton makes anything less than 14 days not worth it, and the hassle of airports put me off flying) I have a btb booked on Britannia which I am looking forward to and I think that is the best option for me. Longer cruises mean people "pace" themselves and shorter cruises could be more lively because of fomo.
On the other hand The Headliners were one of the best I've ever seen!