With mortgages paying down only the interest doesn't this mean people can become chained to the property? Unable to sell due to the value drop and having to own money to the bank after selling?
Negative equity is going to become a real problem for a lot of people who purchased in booming markets over the last few years.
As far as I'm aware, most places are 'non-recourse'. Some people might say "if you can carry on making the payments you'll be fine". This isn't true though. Not being able to move city for a job, being unable to upgrade to a larger place to start a family, or feeling financial pressure to stay in an unhealthy relationship are all very real potential problems.