Is it so much trouble to type, not write mind you, type 'later' instead of 'l8r'?
Well, yes. Yes, it is a difference. Even more in the case of such phrases as 'I don't know' = 'idk'.
But it's only a few extra keystrokes! How lazy can you be?!
Therein lies the misconception: It isn't a matter of effort but one of expediency. This can be seen clearest within the activity of mobile texting. This usually takes place through the use of a numpad or, more recently, one of those slide-out QWERTY pads. With a numpad the difference of two characters can become several more button presses. Again, you can sneer all you want about how little extra effort is required there but can you really tell me there's something wrong with taking the easy route when the purpose, communication, is not adversely affected?
Speaking from the perspective of an MMORPG player, fewer keystrokes means efficiency as well. That also applies to instant messaging.
I will say this though: The shorthand, while appropriate (yes, I will go so far as to say 'appropriate') for texting and IMing, is not appropriate for use on more thoughtful writings such as emails and articles. The latter activities do not have the here-and-now spontaneity that calls for acronyms in lieu of commonly used phrases.
What do you think? If you cringe when you see 'lol', what would you have us do instead? 'haha'?