Try driving from Los Angeles to Chicago in a tiny car some time. Midwest and western united states there is a ton of space between locations. Trying to do that in a tiny car does not work.
I'm not sure I understand your argument. What about small cars makes them unsuitable for traveling long distances?
When I was in college, I owned a Toyota Tercel, a very small car. Drove everywhere with it, without a problem. I have driven from Michigan to Texas with it multiple times.
If anything they're better since they tend to get better gas mileage. Or you arguing they small cars are uncomfortable? Well, then that's a subjective thing that brings little to the discussion at hand.