This was already covered and discussed several hundred posts ago, but a REmake style remake is actually quite costly for Square because they no longer have the original assets for FF7.
The difference between development for FF10/10-2 HD and a REmake of FF7 is that 10/10-2 were primarily 3D. While textures required some work to get it to HD standard, that amount of work pales in comparison to building and rerendering all of the 2D backgrounds of FF7, on top of building new character and monster models and texturing and animating them, as well as essentially making a new overworld map. That is not counting the work they will have to put into sound, music, and the money that will have to go into making new HD CGI cutscenes. In no way is it just "a few fixed-camera backgrounds and models". At this point, they might as well make a new game.
Moreover, the backgrounds of 7 were created with the proportions of the stumpy field character model in mind; if they were to make a realistically proportioned Cloud, the backgrounds would have to be adjusted for a new character size from the references that they could rip from the game disc (assets that can at best only be references, because 640x480 cannot simply go through magic software and come out looking gorgeous in 1080p).
So even if people have been reduced to the bargaining state ("We don't really want a full blown modern game version anymore, just give us something with spruced up graphics"), it's still not that financially appealing to SE. They're better off investing their money into new games.
