It's one of the things that made FF7 great. Turn based battle systems involve more strategy and put more focus on the secondary characters.
It's not an overreaction because SE just laid out the main focus of the battle system right there in the trailer. You have that nice combo meter beside the HP(that everyone thought was ATB), which makes it pretty clear that button mashing will not just be a thing in this remake, it'll be encouraged since the combo meter starts going down when you're not landing any attacks on the enemy.
I don't find action RPG mechanics any more "modern" than turn based. Action RPGs have been around for pretty much the entire history of video game RPGs, they've evolved, just as turn based combat has, but turn based and action battle systems are entirely two different game mechanics. A comparable to this would be like an OoT remake being turned into a turn based RPG.
And calling turn based RPG outdated is like calling modern Civ games outdated because they're turn based rather than real time. But if you play all the Civs in order, you can see how the turn based mechanics have evolved, that's what I expected out of this remake, not a hack and slash.