First of all, any MMORPG nowadays barely live up to their hype, because players are getting neutral to any MMO live and go.
RO and WoW because that time has not many choice, MMO are pretty fresh genre and common to that generation.
Second, most ex-RO are the majority supporters on this game but they have grown old, they don’t involve that much in the game anymore or only few hours in a week, not even a day maybe after a few days hype and nostalgia.
Third, for new generation around college age 18-25 they have many other choices and not really used to such old-school game, they might also too busy in mobile games already.
Forth, the game is not attractive enough with generic contents to play long enough. The gameplay is fun but they need more creative features to make peoples wanna try out the game. Example: Multi-Party Dungeon, more C3 class quest/event/equipment/hidden skill, more challenging boss, Templar can create 10-players party and etc.