I think the use cases for this are weaker than they were for, say, phones, so I’ll just put that out there. Email is used much less frequently as a primary means of contact for services (at least for most of my clients). However, to the extent that it’s started coming up more frequently, it prompted me to wonder why our contact methods aren’t handled in a standardized way. Email would seem to be the last one that’s not normalized at the tabular level.
I really love having the phone and URL tables broken out separately, because it provides the opportunity to include descriptions, types, and other useful meta info that can be used to improve the experience in user facing solutions like our Resource Directory.
Is that an adequate use-case? 
I wouldn’t say that adding an email object is a major impetus for speeding up our next major release, but I definitely think we should include it in our next major release when that’s ready.