It's entirely possible, of course, for someone to just be able and pick up and play these games, but getting back to what was said before, there is no way Seven was made with a new audience in mind. Even besides the way the game was made, it just would make no sense for a company to put that much money into a game and alienate their established fanbase (in this case, Japan) by trying to push it for an American audience, especially after they tried that with a spin-off game and failed. There was no guarantee they'd succeed, and if I remember right Seven had something like a 50 million dollar budget.

Now, of course they marketed the game differently here in America to try and push sales over here (even going so far as to keep it Final Fantasy "VII" as opposed to "IV"). I mean, they tried that once more with Dragon Quest VIII, and while it succeed to a point, Dragon Quest does not enjoy anywhere near the same success that Final Fantasy did after Seven.