I worked on a development team where half of our programmers were in Russia and the other half were in-house and our only form of conversation was IM.

I think what people 12-17 don't understand, and not through any fault of their own but mostly just because of the fact they haven't been exposed to corporate America is that there's a thing called Accountability. People in the business world now feel that e-mail is a sufficient medium for discussing important business matters, setting deadlines, etc. While this may change in the coming years, and definetly will, that is the concensus now. So, for someone 12-17 who doesn't have to deal with corporate America at this point e-mail probably does feel a bit old school.