I think the biggest problem is not that they changed the story. The problem is that changed the story while at the same time advertised this to be a remake of the original game. People expect to revive the original story with this one (with additions and some changes that expands and/or gives more context, but overall the same story they remember)... But at the very end of the game, they will find out that's not the case.

Let's bring up Terminator again. Genisys was promoted from the beginning to be a reboot of the original. The starting point would be an identical remake from T1 (with some added scenes from the future), but at certain point, the story would change. You may not like the direction, but at the very least, Paramount was honest about what they were doing.

Final Fantasy VII Remake on the other hand, is sold on nostalgia for a story many worship and adore. And they won't tell you that's not what you are getting until the end of the first chapter of a 60 dolar, 35 hours long game with an undetermined number of future chapters on an undetermined number of consoles. That's... lying. And that pisses people off.

I don't know guys... It was as easy as being honest from the beginning. "Hey guys, we are doing a reimagining of the FF VII story. Be ready for a surprising yet thrilling experience were nothing is what it seems". That... Or you know... Make an actual remake. Either way, don't trick people into buying something they might not actually want.

Terminator fan here.  I'd have to say Genisys was same as T1 till very beginning when Arnold showed up to fight first T100.

So... Just what I said?

What that trailer shows is not even close to the point blank shot many people will get after playing the game. The trailer shows some new stuff and changes from the original, yes. But it doesn't imply that the story is gonna be rebooted and the original FF VII plot is gonna be discarded. 

What the trailer shows is what many remakes do. Samus Returns is a completely different game than Metroid II: Return of Samus. Even the ending has some major changes. And you can see some of it in the trailers. But those changes only add to the original story. Samus Returns, despite the new stuff, is still Metroid II. Not like FF VII Remake, in which said additions and changes actually make the original story irrelevant, because instead of adding up, it replaces it.

Nothing in the trailer confirms something like that happening. It teases some new stuff going on, but how that will actually play out is impossible to know. Until you play the game.

Apparently, the expansion of Midgard to make up for the 30+ hour game duration is not very well done. The side quests are boring, generic, uninspired... And you can only do them before starting the main story chapter (yes, the game is divided in chapters). Once you start the main story, you cannot acces to the side missions anymore.

Also, the ending has divided critics and players because Nomura has pulled some bullshit out of his ass to somehow transform the remake into a reboot of the original story.

There are also some inconsistencies about the graphics. Some places have quite low quality textures that deeply contrast with an otherwise great looking game.

What you just described is a remaster. FF7HD is currently out right now on steam, ps4, and switch.

Nomura should have refrained himself to being a character designer. Some accounts of his mishandling of Versus XIII/FFXV are truly scary. The man has some weird ideas, and a non sensical way of telling stories that is truly awful. SE should have hired Sakaguchi for this project, he would have kept that nut case in check.