FFVII is definitely more than 50% longer than an ME game. I'm not sure what you're using as a measure of content, but going by "main story +" on this site which seems pretty decent...

ME - 29 hours
ME2 - 35 hours
ME3 - 35 hours

FFVII - 58 hours

If you're going for completionist...

ME - 43 hours
ME2 - 50 hours
ME3 - 48 hours

FFVII - 92 hours

And then consider the fact that the content of FFVII is what I would call "more diverse" than that of ME (although admittedly we don't know how that applies to the remake)...

EDIT: Just to reiterate, I'm talking about the development cost vs. reward thing. In other words, the cost of making FFVII would probably be considerably higher than the cost of making, say, ME (and potentially the entire ME series, although that's probably a stretch) and therefore they would want to justify that cost by increasing revenue. Essentially you get the scale of game you pay for.