I would argue, to an extent, that Nomura doesn't help much either. Another horrible entity that, I think, is really stifling Square are the fans.
Now, I don't mean casual fans of Final Fantasy, or long term old school fans, who understand that each Final Fantasy should be unique and there shouldn't be any direct sequels. Once the game is done, you're done with that world. I mean, rabbid horrible fans that live, breathe and eat materia for breakfast.
You know the type I'm talking about; "We want more Final Fantasy VII!" "Where's Final Fantasy VII HD?" "Kyaa~ Sephiroth and Cloud are my waifu/husbando, otp, etc. etc." They cry the loudest and foulest when a FF title doesn't meet the criteria for their penultimate FF, since clearly they have the most sugoi taste (yeah, now I'm getting out of hand).
Who care if FFVII has dated graphics? It still works, you can easily get it on PSN, and possibly Steam in the future. Square has better, and more deserving titles that could use a HD remake (and in all honesty, none of them need it, because rose-tinted glasses). I understand world building is difficult business, and takes a large amount of time, but I think a lot of FFXIII's world was superfluous. FFIX's world wasn't that intricate with all sorts of weird terms, rules, etc.; and I don't think anyone really cared.
I think, for a lot of us FF fans from yesteryear, we enjoyed a compelling, and at some times, deep story. Exploring a skewed version of our world with fantastic technology, magic, or even magi-tech! Combat was never super deep, and we could always grind for hours on end to make any battle a breeze. We loved the music, the art, the characters. So...where has it all gone? Why am I suddenly trudging through a hallway where everyone is talking about these...weirdly named things? Sure the combat is unique and can be excited, but...what do I care about these people? One's a whiny brat who can't express himself, the other a half-cocked show off to cover his uncertainty. What do I care about the fate of their... Cocoon? Is that...a planet? Country? Oh wait, it's a giant biosphere thing...in the sky...with airships inside of it? What?
Back in...2005? We heard about XIII, Versus XIII and how they were going to share stuff together, and it was kind of exciting. Especially since XII was kind of a let down (it would of done a lot better on better hardware, i.e. more RAM for more environment and less loading). Then XIII came out back in...2010? Still no Versus XIII, and the title, was again, a bit of a let down. XIV came out shortly after and was a major let down. So...where was the announcement for XV (I imagine it's being held off for PS4/720 development)?
Financially, I can understand why they're doing sequels and not main series. For each new title, Square develops a new engine, from scratch (I imagine) and develops technology for that series based around that engine. So with something like FFX-2, FFXIII-2 and Lighting Returns: FFXIII, rehashing your old code, making a couple new assets, etc. is cheaper...but it's not something us fans really want.
Kojima Pro ran into this when developing MGS4, and so they created a new engine (FOX engine) that is more flexible. I believe Capcom did the same thing with their Unity engine. I hope Square uses this approach and create a dynamic and flexible engine that they can use across multiple platforms and to develop a variety of different titles. =\