Long as they aren’t bringing more than the hard side case and a carryon that fits under the seat in front of them.

Most of my flights are traveling overseas. If I’m going for work, you couldn’t pay me enough to check my bag on the chance the airline misplaces it and I don’t get it for a while. So I will always bring a hard sided suitcase on with me.

When I travel for pleasure, I always take a backpack. To me, there are a lot worse things that people do on planes than bringing hard sided suitcases on board. The planes are designed for that.