if i think i wiil need the email address in the future, i save the contact by the name, like everyone else. if i think i will never use the email address again, i delete it. I don't want kaos in my PC google contacts just as i don't want kaos in my phone. I save all my important emails (money transactions info and similar), so i can still find the email addresses in the archives should there be need for that.
I see how that could not be the perfect solution for everyone, but I assure you, it is working very well.