Eddie Smith has sampled the nectar of static blogging and now he's hooked. He provides a very nice rundown of moving from Squarespace to Jekyll.
As for they big "why", Eddie has the saddest and most accurate reason for fighting the good fight:
Even though indie blogging has been relegated to third-, fourth-, maybe fifth-class citizen status on the internet in the last few years, I’m still grateful it lives on through the people who won’t let it go.
If static sites increase the longevity of indie web writing, that’s just one more reason to support static blogging and the individuals that freely share information that empowers others.