MS only wants it for the game they own, lol. MS, the losers of this gen, not the leaders, want this. Very obviously its largely being done by MS for the press. Again, the idea this is some altruistic thing is preposterous. Sony is the status quo, it would be insane to allow other people to play in their ecosystem without paying to be part of PSN.
There is a huge incentive to buy a PS4, because far more people already own it, so if you wanna game with them you have to get one. Cross play is completely in the losing guys interest, and not in the winning guy, Sony. Sony has worked hard to wrestle the mantle away from MS, and now that MS has been beaten comprehensively, MS wants Sony to give up the mantle just like that?
Personally, I really am surprised so many people feel strongly about it. The situation isn't even going to arise very often. Oh wow, the biggest most succesful videogame of all time, Minecraft wants to do this after years of making billions of dollars. Minecraft is an institution. These circumstances will almost never be recreated. No one else is even going to bother wasting money to do it. I think for me, and many people, it doesn't matter if I am multiplaying with Sony strangers or other strangers. Prefer it if its just Sony actually, as that's the best bet you are playing on even ground.