I agree with your main point – my personal email is now, effectively, a slightly unwieldy combination of an online storage space for information I want to keep, a way of quickly getting activity notifications from various web services, and a method of verifying my identity. (Actual communication with most people generally happens over IM or via Facebook or some other web service)

But the fact is that there are other services that do all these things better, seperately, and there’s no particular reason why they should all be lumped into the same app. It’s really only Gmail’s impressive storage capacity and search, plus the fact that it archives Gtalk conversations as well, which keeps it as being central to a lot of my online life.