From an in-game perspective, they might not be strong enough of spirit or will to communicate in such a method.
From an out of game standing, there have been previous postings on the in-game forums made by kobolds (most notably Pik, who perished at the October 2009 event, if I recall), and they have been plot-spun posts with information to follow up on, etc. Completely random annoying posts don't really get anyone anywhere, in my opinion.