why?

How do you spell that no wait did you say M is that upper or lower case how do I type an underscore into this thing oh the word underscore was that .net or .biz too late I typed .com automatically.

The places I've seen that give automatic email addresses have used a formula like first initial, last name, autoincrementing number. I think this is a pretty good system, but if you go worldwide you're going to get nice big numbers - entering name and number almost exactly like you do already. But if you misspell something based on a verbal communication it breaks harder.