The "remake" is indeed a slippery slope. I can't exactly say my thoughts on the matter always sync up with popular opinion for or against them:
- - I feel that depending on it's time, not every generation has the same level of remake viability, with the PS1 era being a prime example. There's simply too much risk involved with modernizing titles that embodied a transitional gen, which the fifth generation obviously was for 3D gaming. Updating 'this' and taking out 'that' with trailblazing games dilutes too much of what they were and what they represented. I think having new 'ways' to play these titles is more appropriate than risking butchering them.
- - Generational circumstances aside, not every game is a ground-up remake candidate because not every experience jives well with modern design habits.. this is exacerbated by the fact that a remake is not a one-way street in terms of quality - the newer gen's bad habits will find their way in every bit as much as the improved graphics and presentation will.
This is a problem, because for many, increasing feelings of unfulfillment with the state of modern gaming is as much of a reason for wanting remakes as the aging state of classic titles supposedly no longer cutting it.
- - Sometimes when people desire a remake it's not that they aren't accepting of their old favorites anymore, maybe they simply want more of what they had and have since lost, just as it was. I count myself in this group.
When I crave something like an FF VI update, I don't necessarily want a game with a complete graphical overhaul, I just want to experience another adventure in the vein of what I enjoyed before. Mega Man 9 and 10 bringing back the NES sprites while being 'new' games is exactly the kind of thing those like me were looking for. The Final Fantasy IV Complete Collection on the PSP was another nice way to satisfy nostalgia while providing new content, improving the original sprite models on top of additional sequel stories is something I wish FF VI would get treated to as well.
- - There is nothing wrong with the "HD update" when used appropriately. An example of this is the Ico and Shadow of the Colossus Collection, a full remake was completely unnecessary. Instead these games received exactly what was, a quality HD touch-up that loosened some of the restrictions placed on them by their native platform and provided fans with easier access.
Yeah, there are plenty of ill-conceived "HD" collections that are nothing more than petty cash grabs, but that doesn't mean the likes of the Ico/SotC and MGS HD Collections aren't worthwhile.
@KingOfOldSkoolPS1 hits are the "usual suspects" for having a remake for the reason that they are very close to the philosophy of modern games, because it was then during the late 90s, when the dominant trends of modern gaming were first established, and for the most part have remained unchanged. Games like Resident Evil, Silent Hill, Metal Gear Solid, Alone In The Dark, or Final Fantasy VII have all the same cinematic qualities as any typical action adventure game of today. They are so close, and still so far away because of their outdated graphics and control system.
Also I agree that one of the reasons that people desire a remake is that they want more of what they had and have since lost. I think this explanation covers me.
The case of Final Fantasy VII is bit different. It's not just one good game, or perhaps a revolutionary game. It's the pinnacle of Square, and of Japanese role playing games. As I read in another comment that you made below, fans actually want a remake of that game because they are not happy with the current state of the franchise, and I agree with that. Most surprisingly, even the inheritor of Square, Squre Enix agrees with that. One of their managers publicly admitted that ever since FFVII they haven't reached the same level of quality in their games.