It works completely different for me. You say: “all initial cosmetics are pretty bad.” I’ve seen them, but i don’t even remember. Because i don’t care. Process of buying should look like:
“i like the game” → “i want to support D4 devs” → “let’s see what skins they got for me”
But people this days buy cosmetics even they don’t like the game. They make devs thinking that they made good job.
I buy those things to play my fantasy.
You claim to buy skins for support but I will call that. That’s some kind of wish you have on how it should be, not how it actually is.
I might or might not purchase the expansion. Depends on me, unsurprisingly enough. I’ve spent maybe 500€ on things in d4? Bit less, let’s tell it at 300€. That’s fine with me but the game’s uninspired, technically finely crafted but the spark of new is not there. Boring even, some say. I had fun though, sure. Was it worth the money? I suppose, fun is hard to come by eventually. You’ll see.
And no, I’m not calling u a liar. I think it’s most sensible to make purchases on the basis of liking the game, that’s natural; what I turn against is that you do it as a favor to them, that’s total and utter dog fart.
So much emotions 
It’s a product you research it and then you buy or you don’t
there is nothing more simple.
For example i’m only waiting for them to show more from the expansion like for example july 18 there is stream about class
You know i’m a wise buyer but i don’t have a problem to drop 100 euros for something that i think is interesting and i think most people that think LOGICALLY are with me on this
It’s unfortunate for you that you just don’t like diablo 4 or 3 or whatever number there is because you think blizzard is greedy