Seth’s blog:

When you can, insist on paying for your software. Our instinct to take the free stuff is often a bad long-term choice.

TL;DR: far more often than not, free apps are almost always some mix of crap, abusive, and/or unsustainable. Stop defaulting to crap, abuse, and unsustainable, buy the real stuff, and support good companies that make great things so great things can stick around.