For the builders, margin is everything. On a $250k house, a few hundred dollars saved on labor and materials for that overhang can make a noticeable impact on the bottom line. It's not just the overhangs, but a hundred other similarly small things that each save dozens-to-hundreds of dollars. Like moulding or fascia made from MDF instead of solid wood, 2" toilets instead of 3", tile that only goes 18" above the tub (if there's no shower there), rooms with switched outlets instead of a ceiling box for a light fixture, the bare minimum attic insulation, etc.
It's a matter of economics. The vast majority of buyers are sensitive to price and appearance (easy to see), not to quality of materials or workmanship (harder to notice). A builder that spends the extra money to build a high-quality home will have a much harder time staying in business.