I figure that 0/40 mortgages are no worse than leasing cars, and lots of people lease cars. I don't see anyone blaming the banks and lending companies for suckering people into renting a car for 3 years.
Leasing a car is totally different from buying a house. For one thing, car is much cheaper than the house, the possibility that the buyer may default on car payment is remote, much more so that defaulting on the house. Indeed, he may be able to borrow against the house to make the car payments.
Also, car leases are typically for three years. The possibility that the customer’s financial situation may change drastically in three years is much lower than the probability that it may change drastically in 40 years. Anything can happen in 40 years. I don’t see anybody leasing the car for 40 years.
40 year mortgages are good only for the lender. Lender collects plenty of interest and even after 5 or 10 years the borrower has paid back very little capital. Seeing that many of them may sell the house in 5 or 10 years, the lender gets most of his money back, plus a substantial amount of interest. The borrowers are suckered into the 40 years mortgage simply by the lower monthly payment. But the advantages are all to the lender.
In Japan they used to have 100 year mortgages. I don’t know if they still have them. These products are all designed to maximize the return to the lender.