I equate things like LOL, OMG, ROFL etc. into the category of emoticons rather that "text speak". These abbreviations came into being, during the early days of e-mail and chat rooms to help substitute for the lack of facial expression and tone of voice in online communications.
Text speak has its place. Ever trying typng a message on a telephone keypad. I would definitely prefer typing U instead of You.
Emoticons do help in conveying a message wherever, you have text only correspondence. But Text speak should only be used where speed and keyboard limitations make it necessary.