I wouldn't. When we got our first mortgage, the bank made us take it over a 30 year term rather than the 25 we wanted for stress testing reasons - y'know, back when they did rigorous stress tests. We started overpaying within a year. Current (substantially higher!) mortgage is also over 30 years and on current payment will clear a couple of years early (ultimately expect to clear on a 20 to 25 year timescale).
I expect at least some of the 40 year terms are given on the same basis and that people escalate their payments when they're able to. But many others won't, of course, which leaves them with woefully long term debt and the banks bearing (IMO) inappropriately high levels of risk.