At some point in the evolution of email/texting/IM, sideways faces :) :) ;) all over the place seems to be an unconscious response to the fact that words alone cannot always provide the context you'd have if you were talking in person.
But wait! People communicated through written word long before the iPhone fell out of the sky, and I'm pretty sure there weren't a lot of telegrams that ended in :) :) :) How have we reached a point where this is fast becoming accepted punctuation in and of itself? I'm finding it to be unnecessary!
Granted, I've been known to be a happy typer, and it's not like I have it out for anyone who tells me to have a nice day. I've used many a smiley face to add just a touch of softness to an otherwise bland work email and when I wanted people to like me. But like anything, marginal utility applies. When you start ending every sentence with a smiley face, where does it stop? It's like telling someone "I love you" every five minutes.
So. What's a happy person to do? I'd say maybe just try to kick it old school and rediscover the time-honored beauties: . , ; ! ? I'm personally planning to really get back into the exclamation point. And limit myself to two smileys a week.
:) There's one.