But that's the thing with the FF franchise, everyone has very strong and different opinions about what games are good/bad. IMO VII, IX, X, and XII were all way better then VIII, XI, and XIII (XIII-2 being arguable). I'm sure a dozen other FF fans would give you a dozen other list. Until FFXV comes out and does XIII-2 or worse numbers it's really hard to tell.
This has nothing to do with Opinoins and all the opinions you have on this mean nothing.
This is about pure raw numbers.
VII, VIII and X are the three big games. Aside from those Final Fantasy has had major issues selling to consumers and keeping them going game to game.
Just acting like a fw awesome trailers and the name FF XV will not solve the continued issue of Final Fantasy being in a downward spiral. We already have the evidence of your XV doing XIII-2 numbers. Not as drastic surely, but the drop is no less scary given how IX, XII and XIII couldn't equal VII, VIII, and X while XIV turned into one of the biggest problems Square has had in a very long time.
It doesn't matter how much we love the games when the audience continues to drop.