Having all the stuff that could happen during the day if it were (if you will) someone's full-time job, instead get crammed into evenings and weekends when you're trying to also do non-chore stuff with your kids (or, for god's sake, maybe get just one measly hour to do something you want to do, alone... or spend time with your spouse, without kids...) and take care of things that have to happen each evening (dinner, bed time stuff) really, really sucks.
Not having chores piling up through the week to ambush you both on the weekend would be amazing. I can hardly even imagine how much more free we'd feel. With two working parents it's like neither ever gets any actual time off that they're not carving out by neglecting something they really ought to be doing (usually several somethings)