stretch affordability if you want.
It is the best savings plan most normal people will ever have to build wealth.
If you are going to optimize saving on housing expenses and are disciplined enough to actually save money in your budget separate from what you spend on housing, I can see an argument for an interest only versus a 30 year, but I think very few people are actually that disciplined and so most should buy the nicest home they can afford on a 15 year mortgage.
If they can't afford anything on 15 years, then I could also see the argument for getting into something on a 30 year or even interest only so that as the market increases it doesn't leave you behind.