Reasons:
1. No Crytek/EA Dedicated Servers
2. Low Playerbase http://crysis3s.com/ / Compared with http://bfbcs.com/ (Even a 3 yr old game beats Crysis 3)
3. Even lesser servers & players in Asia
4. Very limited things to do in Multiplayer & the maps are far too puny

And i thought the hype Crysis is doing in facebook would help boost the game, guess not.