If you can afford the $600/month payment, as evaluated by the bank giving you the mortgage loan, you get a better house with a 20 yr mortgage than 15; more with 30 than 20 years, and a bit more with 50 than 30.

     Absolutely a gimmick; tho also a choice that many folk might prefer to take.

     All gimmicks are also choices.

     What's a better alternative?

     Mine is to offer all buyers a one-time 0% interest down payment loan equal to the prior 10 years taxes paid. So that $100k goes down to maybe $95k (or 4* that amount). [20? 30 years? for first time buyers, never before buyers at 60, also.]