The goal isn't milking the buyers, it's to make sure they keep playing the game, because the abandon rate of NRS game compared to other fighters/games is ridiculous.
If you can just get whatever you want instantly it defeats the purpose.
Also we're not talking cosmetics here, Overwatch doesn't let you pay for gameplay altering mechanics.
There is also the possibility of ingame events to beat, that could lead to specific gear themes (movies, comics etc...), maybe you can earn tickets to participate in game. And buy some if you lose and are out of it.
I absolutely don't see a loot crate system in this game with the business model they went for.
I think they will sell plenty of SHADERS. All those colors from comics, movies, they also confirmed shaders can change skin color, hair, and face, so you could get specific shaders (momoa, cavill, gado etc...) too. That's basically the new "costumes". This wouldn't demand new voices and stuff.