It mainly stems from a desire to reward effort. It seemed slightly unfair to us that a very short post with little going on in it should be rewarded with the same amount as a post which was worked on hard and does include details. It isn't perfect, but I think it's slightly fairer than the generic 5 Khookies per post. If you guys can work out a way which is even better, go for it and I will be sure to implement it if it is good. I think we're at a point now where you as players have as much of a right as any of us GMs to improve on the game mechanisms and make this an better RP

Edit: which is why I have, for the first time actually unless I've missed something, specifically referred to consultation with you guys in the OP