Perhaps the problem is that they are too easy. People will spend hours driving without a break, gradually losing their concentration etc. They are good if they're not too busy. I like driving smaller cars (what would I give for a Caterham or an Elise?
) which tend to make you feel more vulnerable on motorways. A fairly constant speed and plenty of opportunities to overtake slower traffic are great. But they are different to most other roads, which is why there should be some compulsory motorway driving. Even if it's just a couple of one hour sessions.
Twisty backroads are the place to be. You feel far more involved