interest rates for 15 year mortgages are much more similar to the rates for 30 year loans.
If the rate for a 15 year was 4% and the 30 year was 6%... then go with the 15 (because you can afford it).
But when the rates are 2.2 vs 3, it's much less obvious.
I'm probably in the camp of people on here who say just pay more each month on your current loan (it seems you have the desire to have no mortgage which is understandable... my personal preference is to pay as little on my mortgage and use the funds elsewhere).
Paying more each month gives you great flexibility if you were to lose your job or get sick or what if 5 years from now you get a huge pay increase and want to move to a little nicer place or what if your job gets transferred etc... you also avoid the closing costs of a refi (and you save the hassle of getting another loan).