Totally agree.
There's definitely a place for larger cars with 4 wheel drive though. Out where I live with many of the smaller roads ungritted we wouldn't be without some form of 4x4 given the route my wife has to take to work at a small primary school in the middle of nowhere. And if you only have a small car where are you supposed to put the kids and two black Labs that every farmer round here seems to have? Our local Shepherd drives a big 4x4 - sheep dogs in the back and he drives across fields all the time, not sure a Fiesta would work all that well. There are people who have a significant distance to drive along a farm track before they even get to a public road out on farms on the fens, I don't think it'd be fair to tell them they need to ditch their Landrover or other 4x4, and all buy Fiestas and sit out the winter at home just so people in more civilised parts of the country feel better about life.
A lot of these people have these cars because it has to cover being a 4x4 and being a comfortable family car. They don't want or need a Defender AND an estate car for example, they just need something that'll do both.
There are places and situations where these vehicles make perfect sense.
But the school run in Kensington isn't it imo.