I thought it through and my stance is I do think there's a very big difference between p2w and cosmetic only cash shops from a moral stand point in the context of Diablo Immortal and PoE.
I never felt like PoE was trying to push me into buying something. The purchases I've made (0 cosmetic btw, it's been all quality of life things) were on my own terms, I didn't feel manipulated in the slightest. There was no gambling mechanic, it was a straight "I give them money and they give me stash tabs" transaction, there's no catch. I don't need to login every day to keep them, they exist until PoE decides not to run PoE anymore.
The above is a lot different than Diablo Immortal trying its hardest to convince you to buy something because it directly alters the core mechanics of an ARPG which is to make your character stronger by trying to get you to purchase items that make your character stronger. The whole system is set up to make you constantly evaluate "well, should I grind this out 8 hours a day for 4 months or spend $50 to have it in a few days?", and it's painfully obvious.
These elements are also pushed into the game's UI so it's in your face all the time. They also took it 1 step further and introduced a lot of randomness into your real money purchases and they self destruct if you stop logging into the game. I was trying to compare this to a "real life company" like a casino or car salesman but somehow even they seem better from a morality standpoint when compared directly to Diablo Immortal.
So yes, in my mind there is a big morality difference between these 2 games in how they operate their cash shop. One of them feels like inconceivably high pressure sales tactics designed to maximize profits at no cost while the other feels like a game that does everything in its power to kill you with kindness by providing value through entertainment in the game so you end up making purchases because you like the game and want to support the developers, what you get out of that is more like warm fuzzies and some quality of life enhancements (or cosmetic things if that's what you like).