if it wasn’t fun for people, people wouldn’t be buying them
I am not a psychology major or anything, but isnt it that microtransactions are designed in such a way that they hook players in not by being fun but by being a literal gambling? Or in case no lootboxes, FOMO? Like LoL once done with many skins stating "It is a one time possible to purchase, never comes back like ever!!!1!11" to later sell them once again.
Back in a day you either customize game yourself by downloading mods and models, or you earn your fancy skins by being good at the game. Today it is just a purchase. There is no fun in cosmetics beside bragging about them. There might be fun in pay to win, but not for those who doesn't pay. Neither it is healthy fun.