The issue at heart here is clear comprehension of concepts. When someone writes in an unfamiliar or unclear manner, the concepts are not conveyed properly. The English language has enough subtleties and words with multiple meanings that it is confusing enough to start with. When abbreviations and shortcuts and confusing methods of writing are used, the information becomes unclear or even lost. That is why there is a standard to writing -- everyone follows the same rules so that when two people write the same thing, they are supposed to mean the same thing.
I participate in a fair number of forums, and this issue of comprehension is more important on some that others. The most important one is the fireworks forum I participate on once in a while. Conveying exact meanings is an absolute necessity, since mistakes or unclear meaning or incorrect information means that people can get seriously hurt or die. In my mind, this forum is a second tier, because while we are dealing with living creatures dependent upon us for survival, they aren't people. Incorrect information, or confusion, or unreadability means that a fish could very well die. Then there is a third tier, like one of the golf forums I participate one, since the worst that can happen there is someone's swing gets all messed up, but chances are that people or animals aren't going to be hurt as a direct consequence.
So, in my opinion, it is a matter of information comprehension. If you want your information to be as clear as possible, you write well. If you don't care enough about your question or comment to write it in anything but abbreviation and txt-speak, then expect rotten replies.
