Well, one of the basic problems map makers are facing is data licensing.
Let's face it; gathering and converting the source data is tremendously expensive, work and time consuming. For that reason, the sources are very protective of their products. They typically license the data out with restrictions on copying and editing. In most case it is possible to license the source data with the right to edit but that right can not be passed on. Such licences are more expensive. Even more expensive are the licenses which include the right of the end user to acess and / or edit the data. You have to consider that; if the data could be easily accessed and edited, a "map maker" could get the data from their competitor product and only add few features and totally skip the actual data gathering. Their cost would be minimal so they could sell the product cheaply and now, who would want to buy the product from the original data provider? Who would cover the cost of gathering data?
It's kind of like: why don't you guys openly post co-ordinates of the treasure rich places, old forts, forgotten estates and such?