The series has been around for so long, I remember when I was a kid my mom was a huge FF fan on Nintendo, when 7 came out I started to play with her. That's why I like it, it is one of the memories I have of my mom. I'm sure a lot of other people have similar reasons, they grew up with it. It isn't for everyone, not everyone has the same taste. But for me it is my favorite RPG, and how I rate any others.
I hold out hope that one day (in my fantasy world) Squenix wakes up and stops the madness. I would love to see an old school throwback for XVI. I'm tired of the tech theme. But I digress. The reason FF is special I don't think can be answered by one person, it's special for different reasons to different people. And it isn't special at all to some. Simple as that.