Why do casual players seem entitled to cosmetic items added in game?

[Immut]

Apart form the difficulty for 24-Man content, theres one massive glaring issue with this as well.
It's short lived content with long live content reward structure.

Why the hell should people grind this hellscape of a content drop for so long only to collect Tokens to trade in for the things (multiple most likely) they want.

Because that's how rare drops in MMOs work. You do the most godawful time wasting thing you can find and then brag about how you have the thing nobody else has because you did the job nobody wanted to do.