Suburbs built in the 1970s have the same problems as houses built today - rapid, low-quality construction, cheap materials, etc. They're temporary buildings. (Levittown, in fact, was built in the 50s!) At the very least, a new house is further from it's expiry date than an older house. You'll probably find better construction where land costs more (downtown cities) or pre-1950s buildings, but these are quite rare.

EDIT: As a reminder of the endless progression of time, a 30-year-old house would have been built in 1988.