> Personally I think you might be clasping at straws trying to equate every pleasant experience to some type of reward function.
No, here I just focus on why play is fun, you tried to pivot to other pleasurable experiences. Unlike watching sunsets basically every animal plays around as kids, that play is therefore something that is directly related to survival of the fittest or we wouldn't see that everywhere. You need a really strong argument why for humans play doesn't fill that role when it fills that role for basically every other intelligent animal.
> I'd go as far as saying if we worked this simply and predictably, then our lives would be much easier
So you think humanity would be better off if nobody played around and discovered new things? We would be stuck as monkeys in trees then. Play is pivotal to humanity.