As much as I enjoyed the NBA Jam/Blitz reboots, I blame more of them losing their 'charms' on the fact that the NFL stopped the Blitz series because they didn't want their license to be represented by excessive violence, same with NBA ceasing the NBA Jam/Street series' existence (along with a neutered, awful game on the 360) because of them not wanting American Basketball be primarily reflected by 'urban culture'.
Before Blitz: The League existed the NFL had limits on how much crazy shyt Midway could get away with.
So it isn't a 'blame EA' issue. Blame the owners of the licenses.
the JAM Reboot is actually way better than Blitz, at least that game had the original guy doing the directing