But that wouldn't seem to explain the many years of success Roseanne had. Also, as to the comedy, viewed in its time-period, it was a very funny show.
Maybe it's a thing that only people who grow up in that kind of area get (I'm about 250 miles from Landford's fictional location) but seriously most sitcoms just make me cringe with disgust. "THAT's your biggest problem today? I'll trade you any day of the week and you can find out what a REAL problem is."
Here's a potential middle-class The Middle plot line for you: the Glaussners wash the mud off of their off-road 4-wheelers in the street using the Heck household's hose. They do not turn the water off. It runs all week, straight into the gutter, before someone notices and turns it off. The Hecks get an unexpected $300 water bill, which passes unnoticed in their huge monthly stack of bills, as they pay the usual, average monthly amount. Then one day, their water is shut off, and they can't get it turned back on until after Mike's next paycheck.
That's a believable middle class problem. Can you guess why it's believable? Because it's based on a true story.
Personally i don't find any strong relation between identifying with characters and laughing from their jokes. It may add another dimension to the experience in comic dramas, but if i'm watching a pure comedy/sitcom, i don't think it's a big deal.
But i guess people are different.