Or maybe now that a large group of drivers have an impact on Uber, they want to continue to build muscle. If it was something other than accepting UberX fares,

Or maybe now that a large group of drivers have an impact on Uber, they want to continue to build muscle. If it was something other than accepting UberX fares, Uber wouldn't have caved (they're too smart for that). No this points in at the very least a small shift in negotiating power between Uber and its drivers. The fact that Uber caved makes it pretty clear Uber knows it was in the wrong and they are starting to fear a unified group of drivers.