They need a combination of pulling capacity and passenger seating. It's true that many SUVs are capable of towing over 2500 pounds and most of them seat five passengers; some even offer third row seating.
They feel an SUV is a safer vehicle because it's larger and heavier built. And they like a vehicle with taller seating. (There have been concerns about rollover, but most manufacturers are working on systems to minimize the risk.)
They want the cargo capacity and feel that an SUV holds more than a station wagon. (The cargo area of an SUV may indeed be taller, but in many instances is not as long as that of a station wagon.)
They want a vehicle that will get around better in the snow. (While this may be true when you compare an SUV to a rear wheel drive car, it may or may not be the case when compared to a front wheel or all wheel drive car with proper tires.)
They want the offroading capabilities. (Many sport utility vehicles do not do well in true offroading conditions, and the number of people who actually take them offroad is small in comparison to the number of people who drive them.)
But The Truth Is
Most people buy an SUV because they can. It may not truly fit any of their needs, but it fulfills their wants. We Americans are in love with our cars. We appreciate good styling, and SUVs are currently in vogue.
Part of the reason we work for a living is to obtain the things we want, including our choice of transporation. Yes, SUVs use more gas than most cars, but there are hybrid SUVs coming that address that concern. The 2005 Ford Escape Hybrid is one example, and it appears to be a good one. Watch for even more SUV hybrids to be introduced if buyers demand them.
Some of the compact SUVs get fairly decent gas mileage--shifting downwards in size is probably a good option for many drivers. Another trend to watch for is the addition of clean-burning diesel engines to SUVs.
Whether your reason for owning an SUV is "valid" or not, if it's what you want to drive, and you have the means, it should be what's in your garage.
This is an older article, written when SUVs were still covered on the Trucks website. You'll find reviews and details about SUVs built from 2004 to 2007, but for information beyond those years see About.com SUVs and Minivans