If you have something you are recognized for... you will cling desperately to it. Comedian? Forever chasing their best show. Sports legends hanging around too long. Its pretty human to want recognition... even if part of it is genetics and youth. Time is the great equaliser.
In the end - if the odd rituals, diets, and surgery leaves them feeling happy... let them have it. Being pretty and famous is almost a monkeys paw. Sure, everyone ages - but you get to age on a pedestal. There initially for your broad appeal... and then on public display as everyone gets to get their shots in as that youthful glow fades. Ick. I wouldn't want it to be me.