The impression I get is that most SMS'ing goes on not between family members, but with friends. So being single is no excuse!
Seriously, if you don't need it, you don't. I'm not jumping on anybody's case over not using SMS... just cautioning against attacking it, just because so many people seem to abuse it (like the family in the recent commercials from one provider, don't ask me which). It's just a tool. Like the cellphone camera on my Razr that I never use.