without easy to use voice chat, this's basically the only way to play the game that'll actually work...
which, of course, raises the question: why not just separate controllers, with screen-in-screen when necessary?...
For me that's about the way I intended to use the game because that suits my very specific stupid needs.
single screen with just separate controllers is kind of inelegant because you're gonna spend quite a few time in the menus and the GC original dealt with that by not interrupting the action and the 2nd screen doing all the menuing.
That way people could still play and move while the player(s) was fiddling with inventory (it's one of these games with limited inventory).
Even the worst single screen solution wouldn't have been ideal but even I would have found a way to accomodate.
I really think that's an even lower budget project than stuff like Trials of Mana and so they didn't have the budget to rework the game for single screen co op.
No online would have been unacceptable in this day and age so they focused on that.
They gave us cross play because that's probably easy to implement and good PR for them since Sony is no longer against and they can recoup any risk with mobile versions, Switch being too big to ignore especially in 2020.
I think we're giving more thoughts than any higher ups ever did, I still think the people making it are pretty passionate about it. They wouldn't have included FFCC franchise fanservice otherwise (and the bean counters won't mind because they just have to lift models from old existing projects with minimal rework).