Ryan Avent explains one theory why suburban developments are marked by disconnected streets and cul-de-sacs:
The logic behind cul-de-sacs is easy to understand. Roads in suburbs, unlike roads in cities, are for personal automobiles and personal automobiles only — there is no sense of a mode sharing role for the streets. As such, neighborhoods feel the need to carve out special streets for playing. But when a development does this, is redirects more traffic elsewhere. This encourages developments elsewhere to cut off their through routes, too. Eventually, the result is an extremely broken street grid that adds time and miles to all trips — the ordinary and the emergency. At the same time, it encourages the mental division of streets into play street and driving streets, such that on driving streets, awareness of pedestrians and cyclists is diminished.
A complete grid is good for the city as a whole, but there is every incentive for each subdivision to be the one that deviates and cuts off their through streets. When everyone does that, however, everyone suffers. Cities need to make street connections a priority.
Of course to do that while satisfying homeowners’ desires for safe streets would also require a reconsideration of street design and planning. Room must be made, along the street and in drivers’ minds, for pedestrians and cyclists, and on residential streets, speed cannot be planners’ top priority.
I've made this point before. We frequently see the "beggar-thy-neighbor" dynamic play out in Austin. One group of homeowners petitions to close a street through its neighborhood, diverting traffic through other neighborhoods. The city gives into many such requests over the years, degrading the street grid and burdening residents everywhere with increased congestion and longer travel times.
It's an open question, though, whether homeowners would prefer to live on a street grid even if they knew every other neighborhood would be built around a grid. It's hard to find good comparisons. We can't compare a homeowner who lives on a cul-de-sac with a homeowner who lives on a busier through street in the same subdivision; the through street is busier because of the cul-de-sac. Nor can we compare a homeowner who lives in a suburb with a homeowner who lives on a grid in the urban core; the neighborhoods differ along too many axes.
It's dangerous to rely on my own preference, but my guess is that most homeowners would prefer living on a grid if they knew everyone else had to live on a grid as well and if a house on a grid neighborhood were not too much more expensive than a house on a cul-de-sac. I suspect that the benefit to them of better mobility throughout the town would outweigh the cost of slightly higher traffic on the street in front of their house. Suburban New Urbanist developments with a traditional street grid do quite well. Perhaps they would do better with a cul-de-sac layout, but they use the traditional street layout as a selling point, so I doubt it.
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