I know many players on Balmung that are not roleplayers but they picked that server because they like RP to happen around them or because RPs are said to be friendly community. RP label should actually help the server because even if it'll be full there will always be RP players wanting to join in~
And y on earth would anyone create a seprate char on non RP server? This server would be exactly the same as any other just with that extra RP community. Ragnarok is a different case. Many ppl didn't transfer there because they prefer international server (as it was in 1.0) over EU only. With 2.0 and regional servers the ratio is going to change, I'm sure. "RP" doesn't mean "I won't have anyone to play with so Im not going there".