Why'd they do that? So the polls are going to close at 6 their time? That makes no sense.
It costs money to keep the polls open later. Illinois has both early voting and no-excuse absentee voting, so there is no particular need to keep the polls open late.
So basically, if you're a "low information voter" who just plans on voting right after you get out of work, you're screwed.
How many of those are there? It's not as if you'll be able to learn anything about the candidates while at work. Besides, it not the voting booths that get locked at closing time but the doors. Anyone working a traditional 9 to 5 job will still be able to get to the polls in time to vote even if they do decide to procrastinate. It's possible that they'll ding some people this time who didn't notice the change in the closing time despite what I would expect to be heavy media coverage of the change.
Besides, for all we know Illinois may have also decided to open the polls an hour earlier, tho I doubt that.