Gaming is moving to a "service" platform. This will be the new standard, even indie developers are adopting this model. It's not inherently bad, just that certain companies take it to the extreme and that has left a bad taste in many peoples mouths. I actually don't want the expansion model because that means very long periods of no new content, then a massive dump of it, followed by another drought. Microtransactions allow for constant updates that keep a game fresh; POE, Fortnite, etc.
Just look at how D3 was handled. They basically spent years "fixing" the game and when they felt it was in a good place it was essentially abandoned. Why? because they had no reoccurring revenue stream to justify dropping substantial content updates. The biggest thing we got was the Necro. Remember that game developers get paid on average $100k a year and there are often dozens or so maintaining a game. Just imagine the cost. It's not a smart or a sustaining business model to put millions in a game that generates no money for you.
I do think that D4 could go FTP and be successful but remember they have to answer to shareholders and they don't want to hear about the long road to profitability. They want sales numbers. Sad but look at what happened to HotS. Hearthstone was a side project, with a tiny team that blew up like the Hindenburg. D4 is massive in comparison; probably end up costing the company 100's of millions to produce and market.
As long as the game you love is being supported does it matter that they have cosmetic items for sale? Not to me.