It's the max character limit to prevent spamming. Usually this is no problem because people do not post so many long triggers at one time. If this becomes a larger issue we might increase the max.
lol this is hardly ever a problem, I mean I don't think even in the story or RP forums has someone complained about not having enough chars in the post. o_O
I think we should increase the limit, it is sometimes a problem, and if people want to spam, they can still do it within the limits, can't see how that should matter.