Well sure, the problem for most though is two fold: 1) Most average consumers don't understand that. I've been using that for a while now and it works perfectly. 2) Getting replies is obnoxious. You get them in an email. Nor do most people understand how to do this TO the iPhone user, or they're just too lazy to bother typing in an email.
The fact about whether it is important or not is irrelavant... AT&T has dug this hole by... putting off and putting off and blaming it on things that dont exsist... Further say what you will but AT&T suffers from overtaxed networks and poor back haul infrastructure...