Oh no! People derive pleasure from things you no-longer do.
There's a difference between being mature and being solemn. Far too often I see the latter being treated as the former. Being mature is about responsibility, managing your own life, growing to understand what you enjoy and how you relate to others. A lot of people who think they're very adult, just because they don't have fluffy snakes and the like any more... a lot of them I don't see as adults; who've thought about their happiness and responsibilities; I see sad teenagers.