Good summary of the reasons the CUV segment is so hot in the comments:
1. CUVs have gotten so good that for 90% of drivers, their performance is nearly identical to a sedan.
2. The height helps for ingress/exit, especially for older people. Also, parents of young kids appreciate the fact that you don't have to bend down to put your kid in or take them of out of the vehicle.
3. A hatch is much more useful than a trunk. Strollers fit in them much easier. Dogs like them too.
4. AWD is good in light snow and trips to the farmers market. Very few people have dedicated winter tires in their garages.