People using SMS are stupid. You're paying more per message (or getting less value for the money if you have a flat plan) compared to using an internet-based equivalent service (such as e-mail), for a service that's linked to a single device (once again, compare to e-mail where you can sync everything between all of your devices using IMAP), AND causes vendor lock-in (arguably, regular calls have this problem too, except for that then you can at least put a redirection message on the voice mail if it's just temporary (such as, say, being on a vacation), while you can't do this for SMS). E-mail also has the last problem, but then you're, at least, not locking the two services together.
