I think there are plenty of times when a simple "lol" should suffice, especially in the chat forum. Lol is pretty much universally known, and it conveys the same message as "that cracked me up," simply in a more succinct manner. For instance, a funny picture or video posted in the chat forum may merit an "lol", but not really much more. The expression shows appreciation for the thread and provides feedback to the OP, whereas a skipped post does not. On the other hand, there are often cases when people ask a simple question that does not require more than a yes or no answer. Sure, elaboration is great, but should be done by choice and not force. Of course, 5 letters isn't much to elaborate, however the point is that a yes or no answer is sufficient in many cases.

I'm fairly long-winded when it comes to many of my posts. I don't think anyone would argue that. However the 5-character rule aggravates even me. So lets take that kyeruu example you gave and flip it around. I'm going to go ahead and decree by fiat that, at least for the time being, my posts are the most long-winded here. If Mjordan2nd can make a post that falls short of the character limit it should not come as a surprise that many other do as well.