Not like that's better. This is like if they remade Stacraft 1 and sold each campaign separately.
So no, not actually like StarCraft.
That's not a good comparison. StarCraft is a relatively simple game. A remake would play mostly the same; it'd just have some quality-of-life features. It would keep the same units and same maps. Only the graphics would change. Maybe some new writing and voice acting, but these two elements are decoupled enough from the gameplay of the game that they wouldn't demand a complete overhaul of the gameplay. Unless, of course, Blizzard wants to completely overhaul the gameplay and mission design, and raise the number of missions from 10 to 30 per campaign, like it is in Star Craft 2.
Then, they would be justified in charging full price per campaign. But I doubt that's what fans would want.
FFVII, on the other hand, is a story-driven RPG that heavily features exploration. If you want to recapture the impact and magic the game originally had on players twenty years ago, you can't just slap some HD textures on there. You have to completely rework the game from the ground up.
Everything. Character design, battle design, level design, scenario. The latter three elements alone demand a significant overhaul of the original game. Kitase has said such and he (correctly) posited that if you want to remake that game with today's technology and standards, and meet twenty years of fan nostalgia and remake expectations, they cannot make a single game. It's just too ambitious. Remaking FFVII in a single 50-hour-ish game today would not meet expectations. Not only that, but it would have to cut some of the content of the original game. And
that would be a fatal sin.
I don't know how many games it would take, but it's more than one. So at least two.
edit:
here's an example. Remember when you got to the Market in search of Tifa? Remember how that place felt
huge and
alive and
impressive back in 1997? "It looks like a real place! I want to visit that myself!" you might have told yourself.
Now take that market design exactly like it is, and imagine it in a 2017 game. Picture it. Picture walking your character in that space like you would control Geralt in Novigrad. Does it feel rather small and... lame? It sure does to me. Now try this exercise with the entire game. And keep in mind the gameplay is real-time like in Kingdom Hearts. And that they want to heavily expand on the story (Kitase said he wants Midgard to be more explorable than it was in the original game).
That's why they can't make a single game. It just wouldn't be enough to contain everything the remake deserves.