Someone made an insightful comment on HN a couple weeks ago: "housing cannot be both affordable and a good investment." ( https://news.ycombinator.com/item?id=14857591 ;) )

With interest rates as low as they are currently, housing prices are correspondingly inflated (via increased purchasing power for a given/fixed monthly payment). That's pushing us towards the "good historical investment" side of the pendulum, but if interest rates were to return to the 1980s' double-digit figures, it would swing back towards affordable.