The RP forum moves roleplay from the game where it belongs and is in context with the CHARACTER to the forum where it is out of game and out of context with the character and even the player account, connected to the forum account which for many people is not immediately connected. The disconnect is considerable for readers unfamiliar with the player. I do think that people who enjoy roleplaying should do so in-game.
The RP forum is the replacement for the RP mailing list, which, while it certainly had its problems, I still feel was a net positive for the game.
Even though I haven't been writing many narrative RPs lately to post, I think that closing the RP board is not the right direction to be going in. I would rather see it promoted.