As long as the game's orb economy isn't balanced around this, making orb acquiring intentionally slow in order to pretty much force you to buy them, I don't really care about microtransactions being there. They're only ever a problem when their presence leads to altering the games' progression system to a grind.
Matt Walker has said this is not the case here. However, it's still a greed based decision cause if the game is not balanced towards the grindy route, that only means microtransactions are just there to take advantage of the impatient people who want as many moves (or items) as possible as fast as possible. Which, if it truly was purely a matter of "player choice", as Itsuno put it, then they would simply sneak in a cheat code or something to unlock them all instantly.
That said, I'm not particularly worried about it, this is pretty much the same thing they pulled with DMC4SE. People ignored and didn't use microtransactions then, they're most likely gonna ignore them again now, so I doubt they are gonna be successful here.
And although Matt has always been pretty transparent so far, if it turns out he's lying about the game economy balance, we're gonna find out when the game comes out, and goes without saying that I'm gonna be ****ed.