Privacy and evilness issues aside, there's always the problem that what was once awesome and free is unlikely to stay so forever. New policies (max attachment sizes, storage restrictions) etc can also ruin the service.

I pay a very small amount to have my own mail server on my own domain. It is unlikely to ever change (great for long-term networking) and I control exactly how crappy or excellent the service is.

Considering how important email is to each of us in our daily lives, even non-hackers, I'm surprised more people don't pay for it.