The reason for this that everyone focuses on, understandably, is stagnant housing supply. However, housing can also be seen as an asset. Just as low real interest rates boost the stock market because a given stream of expected future dividends looks more attractive, much the same is true of housing (where dividends become rents). Stock prices can rise because expected future profitability increases, but they can also rise because expected real interest rates fall. With housing increasingly used as an asset for the wealthy, or even as a way of saving for retirement, house prices will behave in a similar way. A shortage of housing supply relative to demand raises rents, but even if rents stayed the same falling expected real interest rates raise house prices because those rents become more valuable compared to the falling returns from alternative forms of wealth.
That is why a good part of the house price problem comes from the macroeconomy: not just current low real interest rates, but also low expected rates (secular stagnation). The idea that house prices aretied down by the ability of first time buyers to borrow (and therefore to real wages or productivity, modified by changes in the risks lenders were willing to take) seems appropriate to a world where the importance of the very wealthy was declining, and most people could imagine owning their own home. We now seem to be moving to a more traditional world (remember Piketty) where wealth is more dominant, and with low interest rates that may also be a world where renting rather than home ownership becomes the norm for those who are not wealthy and whose parents are not wealthy.