Well, we added air conditioning, and doubled the square footage per family member, the government poured money in, and a few major markets skyrocketed…that's it. If you want a 1970 sized house with no AC, no garage, you can grab one for $138k in many markets.
Government regulations increase the costs and time until occupancy. Massive increases in regulations and permit fees. It is not "greedy" developers that drive up the cost of housing — it is incompetent busy body city and county officials and the constant, never ending adoption of codes and regulations.
The massive influx of H-1B, green card and illegal immigrants driving demand and higher prices.
The money. They broke the money. Each President, each Congress, and the Federal Reserve have engaged in bipartisan collaboration to steal America's wealth, hollowing out the middle class. The federal reserve inflated away the value of your dollar.
But the government decided to "help" us.