Messaging 24/7

In a comment today about Yahoo's "new" text from e-mail service, an observer at MediaPost described one user scenario: "In particular, parents can now more easily reach teens at school, where they can inconspicuously check for text messages."  To make a comment that shows my age (and is not meant to pick on the poster): Why do we feel the need to reach teens at school via a text message?  Many generations before this one got through school without being that connected.  And when my kids reach that age, I'm not planning to contribute to the inevitable load of both new and old media distractions from classwork.  I want to teach them that one part of 24/7 connectivity is the option of turning it off.