First, Quabbin IS a fantastic fishery, Barkhamstead is not as Dusty pointed out.
There may have been a codicil when the Q was created back in the late '30's and early '40's that it would be open to the public for recreational and fishing purposes.
Third, the Q has strict personal use boat requirements and if your boat is certified for the Q and you fish somewhere else, you will have to go through the certification process again before you could get back on the Q.
There is a possibility that the management of the fishing portion for Quabbin pays for itself through certification fees, fishing, parking and boat rental fees.
I doubt that the MDC is in a position to implement those kind of measures.