What is the alternative? Live in the city in dense, tight, expensive housing?
FWIW, many suburbs do have supermarkets and stores in their downtowns/mainstreets. I can walk...10 minutes or so to my local supermarket. But I choose not to do so because I can drive there and buy a week+'s worth of groceries and supplies in one go. I don't think most suburbanites hop in the car to get a single bottle of milk.
As much as there are people that prefer living in cities, there are people that prefer living in the suburbs.
A young twentysomething single me would have preferred living in downtown Manhattan and wouldn't have minded living in a 300 sqft studio, meeting friends, partying, partaking in cultural experiences that only a major city can offer.
Thirtysomething married me finds that scenario unappealing. Having a SFH in a quiet suburban street with a backyard to BBQ in, a garden to tend, lazy weekends with no cultural activities whatsoever, and a car(!) to drive around in is what I want... short of being extremely wealthy enough to have the best of both worlds.