I'll take a stab at answering. I believe those metrics do still apply today because they illustrate affordability. The fact that more of peoples incomes are required to pay for their mortgages is not a positive or sustainable thing. Years ago one income could support a mortgage, now two are barely cutting it and this is even with record low interest rates.
You're probably right, I don't think it is positive, it's likely that it's not sustainable. But those are value judgments. I'm trying to take one step back. Why would what was considered affordable in a one income age be automatically considered affordable today? Maybe housing is going to get permanently (or long-termly, or medium-termly) less affordable due to a mix of economic, political, societal etc. factors, and subsequently only becomes sustainable or available for wealthier segments of the population?
Would we judge public health based on indicators that were based on trends that did not reflect the demographics (age, ethnicity, race, etc.) of our modern Canadian population?
Would we would try to assess how long the Red Wings will keep winning at home through metrics that are heavily weighted by data from the Original Six years?
Would I not recalibrate price:rent ratios to reflect changes to rental stock, consumer behaviour, consumer spending, income equality, gov't incetives re: housing development vs rental development, etc. etc. etc.?
I'm kinda ranting...well, more than kinda, I know, I'm sorry...I just find this stuff interesting because at my work we're often called on to assess the 'evidence' put forward by corporations, NGOs, once in a while gov'ts, that are used to justify actions and policies proposed or adopted. The first things we do is look for the metrics used to support the evidence (and those that are absent, sometimes conspicuously.) The second thing we do is try to assess the metrics to see how relevant the underlying assumptions and results and accepted conclusions of those metrics are to today. I haven't seen that happen for housing yet, and haven't seen a good answer for why not. When I see someone like Athanassakos state something along the lines of "I can't see why it would be any different" I know that I can think of a whole host of factors that might make things different (on both sides of the debate), and I know that type of thinking wouldn't last two weeks in our enviro.