I was just about to post, complaining about oneworld's endless marketing babble over e-tickets, while they are in fact not available on any inter-airline routes I am familiar with (see www.oneworld.com for recent gloating) . So far neither CX nor BA sell e-tickets ex Europe or Asia span two or more carriers, but reading your post I see that at least AA is doing it now. Maybe the rest of the world is behind a step or two here.
As for the OP question: e-tickets are cool. You don't have to carry any ticket around and all the information is in the computer. My experience with single airline e-tkts is that when you make changes the airline's hotline people are better informed about the ticket and the conditions it carries, they actually 'see' the ticket on their computer screen, so no need to provide copies per fax not to mention stop by an airline office. Very convenient.