People have different reasons for complaining about balance... As stated before PVP is a big one. For others, we want something not based on real world cash. Not all of us are 10-17 year olds with mommy and daddy's credit card, or the 30 year old who does not pay for anything cause they still live with there mom or dad. Some of us work two jobs to support a house hold and children, and don't have the luxury of spending money. So we just want something we can do in our down time(those of us who are gamers that is) that doesn't take cash to be the best.
There are many reasons, everyone has a different one to complain for.