That's a valid point, though a lot of us, myself included, spend time both in the city as well as rural areas, so it's nice to have available. I don't have a truck at the moment though. Something else to consider is that trucks are very cheap for what you pay, fuel economy on them has improved quite a bit, and insurance/maintenance is very low.
But yeah, there's a fair number of drivers that have them "just because", rarely using them for much of anything. My brother is an exception to that, he has a full-size Titan 4-door 4x4, and uses it's cargo/hauling abilites at least 2-3x a month, and has some property in an area where it's a good idea to have 4x4 capability. He also has a car that he uses more often than not as well.
What's good for the UK is often not good for the US and vice versa, and there's nothing wrong with that. I hope to visit there sometime, have a few pints (or more, lol), and check out a lot of cool stuff you rarely or never see here, such as TVR's, pre-19th century architechture, little diesel runabouts, rowdy football matches, etc. It'd be awfully boring if there weren't such dramatic differences between our nations.