I've never been big on insert characters/silent MCs; I think a written, defined character is always better. And that's still role-playing to me. The difference is you've been assigned a role rather than making up your own, and hopefully it's a character you can empathize with and relate to.
But yeah, this I feel is just one of those things that comes with being a AAA franchise. It's like when people dream about a new mainline game that's 2D. Yeah, they could do that, but chances are the catch would be it's really just a stop-gap between the last and next mainline games (and at that point if may as well just be a side game). Because a 2D FF would be cheap to produce and sometimes that's great (the industry would benefit from a lot more of it!), but it would also be limited in its appeal. When you have an established franchise that can actually put up big numbers, you tend to want to make a big investment in hopes of a big return. You wouldn't be doing that with a 2D FF.
High fidelity graphics, voice acting, and honestly at this point, yeah, combat that's a little more visceral and involved than a turn-based system; these are things any mainline FF simply must do now because ultimately SE isn't just competing with other RPGs for RPG fans money and attention. They have a big media brand that has to try to capture as many people as possible while hopefully maintaining it's identity and artistic integrity.