You don't think GMail needs that type of service because you've never
needed access to an email and found yourself locked out of your
account for whatever reason. It only has to happen once. I think I was
lucky that it happened to me only a few days after I had an account so
I am more mindful of this issue before I lose access to something that
really matters (in other words, I'm keeping my primary email separate
from GMail).
Yahoo and other webmail services have POP3 options. You may have to
pay for it, and you may not want it, but if having a local copy of
your email is a priority for you it's possible. Currently, it's not
possible in any way shape or form to retrieve GMail email if the
service is down. Therefore, as much as I like the service for what it
is, I will not recommend GMail to anyone for use as their primary
email.
Right now, Google gets away with a lot by calling it "beta" or
"limited test." When the service is open to the world, they're going
to have to do better than that.
You're fooling yourself if you're complacent with the argument, "I've
been using GMail for <whatever> months and I've never had a problem."
I firmly believe that backups aren't there for IF you have a problem,
they're there for WHEN it happens. No one is immune.