You'll be a debt slave for life and accumulate equity slower. You can always refinance later and get a shorter term mortgage, but your monthly payments will be much higher then. You might not be able to afford it and then you're stuck.

People have a maybe 80-year life span. So if you get a mortgage at 30 years old and keep it, you'll be gone or almost gone before you ever own your house. What a kick in the ass from the government for even suggesting this scam.