I don't think there's a very complicated question to answer - SUVs are sooo much more comfortable to get into and drive than regular cars that it's not a surprise they have become the default vehicle type for many people. I'm only 29 and having developed some joint problems I'm now buying an SUV for myself, purely because getting into a regular sedan/estate is a bit of a struggle, but getting into an SUV isn't. The same applies to the driving position - even in the uber-luxury saloon like the Mercedes E class the fact that you're sitting much lower puts a lot of strain on my legs, but sitting with my back higher up in something like the LR Discovery makes driving much easier.

I'm trying to offset the emissions aspect by buying a plug-in hybrid SUV - so at least my plan is to do 100% work commute on electric power alone.