T28D, exactly! That is why there is such effort by ASTRA and the airlines to facilitate industry funding of the roll-out in GA aircraft. For ASA, it means being able to expand the J-curve to where surveillance is needed. The mineral provinces and major regional aerodromes for a good start. For the airlines it means lower fees after implimentation and better user defined routings. Those routings also have a better environmental impact.
Yes, there is no extra benefit for GA having a garden variety transponder as opposed to a ADS-B transponder. Remember, you only need ASI, Altimeter, Compass and Clock everything else is just extra to meet different certification requirements. It is just handy to have all those other instruments, although you do not legally need them it just makes it easier to do your task of aviating, navigating and communicating. ADS-B is no different for GA VFR. In this case, because someone else NEEDS it. It NEEDS to be paid by someone else! Is that simple enough?
EDIT- before you get on your horse there T28D, Get the link and read it. I am only trying to point out how it works for people like you!