Well then, d***it, why did Illinois have to have a constitutional amendment creating a right to vote in 2014?
My apologies for being so low-information about this.
It was a response to Republican efforts nationwide to restrict voting. Any lawmakers/party trying to restrict voting in Illinois by any measures, such as repealing same day registration and/or instituting voter ID would likely see their efforts fail due to this amendment.
Personally I welcome such an amendment, even if Republicans have no real chance of taking over the IL legislature anytime soon. Every state should have this kind of amendment passed if you ask me. I am actually sort of surprised more Democratic states aren't pushing similar measures, but then again, they might not see the point.