That's how you know it is a purely political move and not a general policy designed to improve voter access. Most of the package of changes were aimed solely to improve chances for 2014 with no risk in future elections if the dynamics are different. The Dems got burned by the success of Cohen for LG in 2010 using the Feb primary established to give Obama a jump in the 2008 delegate count. They don't want a repeat of that type of election reform.
Even as a Democrat who would support Quinn, I think passing a law like that is ridiculous. I'm supportive of expansive voting rights laws, including same-day registration. However, it is an absurd and blatant partisan move to enact it only for this year. It really is inexcusable for a law like this to be in effect only for the upcoming election.