Because I don't want to engage in illegal activities and because I don't want to blindly purchase games for large amounts of money?
I'll look into the NES game, and if I actually end up liking it, then it would make sense to move onto the GBA games and possibly the Gamecube game, which by that time, MAY be at $20 is Nintendo can afford it. I just won't be playing any of these soon because FF Tactics is like a 5000 hour game.