My parents share an email address too, but that's mostly because my mom refuses to get her own. I suspect she's a bit of a technophobe. Either that or she just doesn't want to deal with emails from her crazy side of the family. She also refuses to get her own cell phone but woe to me if I don't answer mine whenever she calls.
I hate having multiple email accounts myself. I did that back in the early days of email and found it to be tedious to remember to check them all. Now, as much as I hate spam, I just use one personal address for everything and get militant about unsubscribing to unwanted email and using filters. Every year I go on a hunt and destroy for online/customer accounts I've created but haven't used. Then again, my address isn't named something crazy or unprofessional.