Jesse puts it so well. Maybe I'm biased, as my first entry to the franchise (and favorite of all time) was an outlier in some ways, that being X and X2. But I've worked my way through the series and I think that at its core, what makes a final fantasy is the grandness, the outrageous "yeah you're fighting in space, deal with it because it's COOL" boss fights, reoccuring characters, and the like... Fantasy of it. 7 was so, SO different from any before it, and now it's the most beloved overall entry. 16 felt like it was made by people who love the franchise, which is something I can't say if every one.
Plus, the FF community hated 12 for years, and that's just wrong lolll.