I don't get the bitching. Is it brutally expensive? Yes. Do you have to buy it? No. In terms of stats the gun is nothing special, the armor is quite good, but not essential. For a one time crossover, it's fine.
It generates FOMO though. I remember when you didn't have to pay for stuff in games, so I personally still find it very shitty to have to buy skins etc.
I’m still a bit unsure how plausible it is to make a multiplayer game, keep it updated, and not sell content within the game.
The good devs restrict it to cosmetic options, but I can’t say I’ve moralistically stuck to that kind of perfection - I’m okay with new weapons/characters as long as they stay balanced against old ones. It becomes a sort of hazy issue.
They hire psychologists to explicitly figure out how to better make sales. Logical thinking will not win. Microtransactions, which consists of crap you don't need, is a billion dollar industry and has bankrupted numerous homes.