I agree with most of what you said other than that refinancing is expensive. Banks offer several different rates. For the lowest rate you will pay the bank, but you can also choose to refi at the breakeven rate, or even take a higher rate and let the bank pay you in the form of a principal reduction. I will be doing the latter as I step down from my 6.5% rate.

Making extra payments does not lower your monthly payment, but it certainly saves you a boat load of interest over the course of your mortgage. I definitely make extra principal payments every month, and even though I've only been in my mortgage just over one year, I've cut off an extra year from the back end. Currently every $500 extra I pay towards principal cuts off one month from the tail end, even though my mortgage payment is nearly $4,000.

I do think the recast is a great idea if you get some inheritance or some other lump sum, but I think the interest you save by putting even $100 extra on your mortgage each month is 1,000% worth it.

To your point, you should have a decent savings account for emergencies first, but I think you can do both at the same time - you can pay extra to your mortgage and add to your investments.