This is debatable, if the Game is Free like Fortnite Battle Royal is, than its obvious that these things will be charged for and quite frankly, its fair. Nothing is free.
And to be fair to epic games, it is plastered EVERYWHERE on the battle pass that all it offers is cosmetic rewards which give 0 benefit in game.
Fancy hearing me on an amateur podcast with friends gushing over one of my favourite games? https://youtu.be/1I7JfMMxhf8