I think the concern some people have is that it's a slippery slope. Sure, right now it might not be too egregious, but if this behaviour is just accepted, publishers will want SP games to be designed around mtx. There's no limit to greedy peoples' imaginations when it comes to squeezing people for their money, so god knows how they'll limit your ability to play games without putting in either a lot of time, effort or money.
This has been happening for years. Shadow of war (2017) had orcs in loot boxes, every assassin's creed since, and including, black flag (2013) has had microtransactions in some form, odyssey (the last one I've personally played) had a rotating cash shop in every city. I know it's another Ubisoft game but farcry 5 had cosmetic microtransactions in a game that is permanently in first person. You could only see your outfit on the change outfit screen. This comment isn't meant to come across as antagonistic but I do find it strange to be warning about a slippery slope when we've all been riding the toboggan for years.