Well I think (hope) Ghost games/ Electronic Arts realised by now, that they didn't match the desires of the gamer base with nfs payback. However they introduced Alldrive so when can hang out and freak out a little bit and make some great pics of our cars.
In my opinion NFS payback is a good basement for future games. But there have to be some major improvements. Like public events. Design contests, levolution occasionally on the map to reach maybe events in a mountain or underground. Through this you get a much deeper and greater game experience.
One of the most frustrating things about payback is the wrap limit of 50. In an arcade modification racer this is awful and a big joke. Of course one could delete slots to make new ones. But who would delete a wrap he made within 3-4 hours? No one really.
Also the variety of bodyparts and kits should be wider, so the cars of all Players look more different.