Medieval Fantasy RPGs: Too much?

Geez... why almost every year, whether East or West, they always make and release medieval fantasy RPGs? I know I dig anime-ish RPGs and love adventure (for rare items). I'm even attached to my characters (that ended up to be brought on my own RPG Maker game in the works), especially to my Holic Online, Luna Online and Fiesta Online characters!

But why on the name of Arthias (WoW-Boys) or Luna (Luna Online's) can't MMO makers make more Modern Fantasy, pure Sci-Fi or Sci-Fi Fantasy RPGs? I know there are only few sci-fi (+ fantasy) MMORPGs like RF Online, Anarchy Online, Neocron, Matrix Online, Imagine Online and the recent 2029 Online, and a very few Modern Fantasy RPGs like Ran Online and N-Age, what's wrong with the companies? Is fantasy too easy to make?

If I am to make one (Part 1)?

Make the game set at around 2012, the year of the rumored End of the World (according to the Mayan Calendar), the game shall take place in a bustling 1st-world nation under quarantine due to a cult that just opened a gate to Hell. The Hell they've opened is a series of duplicates of our world, according to the Grand Demons' motifs.

Since the game's premise is abou