Most domestic flights are short duration trips, a week's worth of clothes fit in carry-on suitcase, and the other stuff (laptop etc) can go in a backpack.

In all my domestic flights in the past year they've had to ask people at the gate to volunteer their carry-on suitcase to be checked into the hold because they didn't expect to have enough room in the overhead bins.

I usually volunteer because: it's free, I don't mind waiting at the pickup, and it's slightly more comfortable when getting off the plane.