Save me from Textspeak

Look, I can understand the value of Textspeak when using a mobile phone, even though I can't bring myself to use it. However, why does anyone sitting at a QWERTY keyboard feel the need to use a puerile collection of letters and numerals to convey a message? I'm not talking about 15-year-olds, mind you. Oh no, I have friends, some of whom aren't that far off being as old as me (yes smartarse, that is old) who didn't grow up with mobiles. "Grumpy old bugger," you might well say, and you're probably right, but am I the only one irked by this?