Your comments

I, personally, find it difficult to write av answer to a post only containing one or a few lines. When the counterpart doesen't give anything for you to build on. But that might just be me. 

What I think (and have experience of) is that a limit like this motivates users to develop their writing, for example by reading other topics.

I understand your concerns for new users, but I think that holdig a certain standard will help people learn the RPG format. A solution could be that the 50 word requirement is a possibility, like rating.