I don't agree, I'm hosting my email myself on a Debian VPS with installed http://iredmail.org/. I have unlimited domains, customizations, full control and there is virtually no maintenance needed, just regular updates.
Sure, but then you're paying for both a domain and a VPS, and you're spending a little time on setting it up - whereas with Gandi (or other registrars that include IMAP with domain purchases) you're only paying for the domain.