What's the alternative though? It's not like Microsoft and Yahoo's email/calendar services are much better. Use a paper calendar and run your own private email server and hope you never have to run for president?
For calendaring, I rely on Apple; even if they were to somehow vanish, I'd still have 3 copies of my calendar lying around.
This is an absolute minimum of money (under $20/year), effort, and disruption to your current habits. Plus, you get to use whatever vanity email address you want.
Why not? It works for a lot of people. I don't understand why some people are so eager to hand their personal data out to 3rd parties. This is a very do-able solution.