I feel as though this could quickly move into conversation about how most people aren't proactive enough to start a game for a fandom they may be particularly interested in (for whatever reason), the extremely short lifespan of the average IJ RP, etc. Which is to say: I feel you.
Forum RP is forum RP, journal RP is journal RP. Personal opinion is that people tend to find their comfort zones, then cling to their newfound preference at the expense of other RP mediums. Forum RP definitely has potential, just as PbeM did back before that went out of style. Unfortunately, once folks are comfortable it's hard to coerce them into transitioning into something else.