I blame Korea for oversaturating the market with f2p mmos and with the mmo genere filled with medoicre to decent games most players decided to settle for mmos that used a highly polished and streamlined version of the Dungeon & Dragons or Everquest formula.
Secondly developers greed caused them along with gaming website to lie about having unique and innovative mmos to genrate hype and sales. Then after 6mos the servers are barren and developers turn their mmo into f2p crap to try to recoup loses.
This lead to the stagnation of the mmo market and players not caring anymore about the next new shiny.
Most developers know that the mmo genre needs new innovation. There are several genres that they can pull from Soul Calibur for combat system with gaurd impact, perries and combo juggles. Bloodorne for boss encounters. With designing a persisten world should go with Witcher.