Adaption executers, not fitness maximizers. Humans probably have specific hard-coded adaptations for the appreciation of some forms of art and play. It's entirely plausible that these are no longer adaptive in our world, and are now selected against, but that this has not been the case for long enough for them to be eliminated by evolution.

This would not make these adaptations particularly unusual in our world; modern humans do many other things that are clearly unadaptive from a genetic fitness perspective, like using contraceptives.