RO Itself is pretty straightfoward, too. And a game that requires you to move a nerve cell if you're totally new because of it's "simple complexity" of mechanics where even a vet gets surprises and Gravity doesn't really spoon feeds you everything (like in other MMOs kids are used to). It's not always the community. The server is even more straightfoward due to customs and stuff. Like, people that want to WoE, will level and gear their chars just to plain WoE. The others don't know, they would just level to be 99. And when they do they quit.
One thing that irked me most from a close friend that left for WoW is that leveling is quite easy post-trans and it's easely soloable if you do it right (this happens in both officials and here), custom items making it easier even then. In both cases there isn't real partying unless you're with friends and that slows your power leveling. No friends? I quit, too boring!
It' takes time to completely master a char here (not saying it's hard), I mean I love RO's unforgiveness when you do something wrong in a hard map (die or wipe out), I've never seen that in another MMO (and is what makes RO fucking fun when you can handle the pressure) but that's just me, other newbies would take it as harsh and leave (lolwut I died in Prison I nid SQIs to lvl this I'm quitting).
That's another problem, newbies feel the pressure that if they don't have custom shit they can't do anything because they see others throwing KO's around. What they don't know is that they don't really need that to prove being useful. A skillful player can do as well as a noob SQI spoiled one and a SQId skillfull player is god-like and I've proven it in Prison when I actually saw a nub Wizzie doing something for himself, using all kinds of skills to defend himself like a man, it's then when I offered him to party him because I found it that he deserved a hand for a small while for his good job.
They see that, they crave for being them and then quit becasue they don't want to work for it (spoiled kids).
There are more and more reasons can I be like this the whole day, but this is already a wall of text lol.