ORIGINAL: rcpattern
There are many threads on the weight issue. It has been debated many times over. If you do a search here you'll find it. There are some strong supporters both ways. Eliminating the weight rule is going to mean bigger biplanes with bigger gas motors or electrics and the price will go up. Many people have strong feelings opposite of that, but it doesn't look like there is much sentiment to change the rule at the moment. Planes don't get weighed at local contests, so unless you are going to the NATS, it really doesn't matter.
Arch
So the spirit of the rule is to keep the planes from getting too big. Makes sense. Maybe a better rule would make bipes carry a smaller wing span.