The fact that many people made stupid mistakes during the Celtic Tiger should not be used to write off a very useful mortgage product.
I come across many people in their 50s, who have a mortgage of €100k on a house worth €300k. They will not have the capital paid off by age 65, so the lenders are classifying them as unsustainable. This is absolute nonsense. If a mortgage is unsustainable, the alternative of renting is far worse.
Now turn that around. let's say a 55 year old renter with €200k cash wants to live in a house worth €300k. The bank should be delighted to give him an interest only mortgage for €100k if he can comfortably afford the monthly interest or €250.