That's rather similar to how I saw it when I first joined, Morinare. :3 Though to me most RPs were more a matter of IC boundries than OOC boundries, especially since I was new and didn't know anybody. If you see an RP going on, don't consern yourself too much with trying to get involved, just throw your character at them in some way. The good roleplayers will resist you ICly, not OOCly, and as I experienced the resitance gradually dropped as my character got move involved and wrapped up in their story.
If you encounter people roleplaying in a public channel such as Grassy Plains or Role-Play that are saying, OOCly, that they don't want you interacting with their characters then it's gone way too far and they either need lighten up or take it out of public. Otherwise, the way I see it anyway, so long as you go into every RP with the mindset that you may not become a core contributor to the story then it doesn't matter OOCly how your character acts ICly. It will obviously matter ICly, in the way that if your character is too pushy it may make the other characters more resistant, but that's why I love RP in Istaria. OOCly it wont matter as long as the other players don't feel you're trying to OOCly make them change their character/story just so you can have easy RP with said story.