It only took me one use of a mobile phone to text before I threw attempts at proper spelling and punctuation out the window. Perhaps one day when I finally conform to the standards of society and buy a smartphone and develop my thumb skills, I'll become more able to spell and punctuate within a reasonable amount of time, but as it is, I don't hold it against people anymore.
In some cases, I actually endorse it. I would never approve of anyone texting while driving, but if you absolutely bloody have to, don't take your time and finely craft a letter in triplicate.