Now your definition of an adult is someone with good communication skills. That isn't a good premise to continue because that that implies that, for example, dyslexics, or people with poor grammer, can't be adults.
In all reality (and I have tried this numerous times) if you type out a long well thought out post you will get "crushed under the wall of text" and nobody reading it or NOT getting the response required.
If you start a post off with "zomgbbq dis is da suxxxx" you will at least get a response. Which, in the end, is the only reason to post on a messageboard for all to see; To be 'heard'.
This is why you see multiple threads, and people posting in general discussion rather than the individual forums. Not because you want to get your message across. But to express yourself.
There is no point on cryptic or anyone enforcing how they feel a conversation should be. They will most definetly try though.
while i can see your side and prefer it, you have to realize that the age of twitter and facebook (both stupid and pathetic forms of communication) have defined many in our society today. it is the only form of communication that most will even consider looking at.
so, anything worth reading, will literally be less then 140 characters, or posted on your page so others can read about your life.
it is unfortunate that facebook has ruined true communication paths and the twitter further ruins it by shortening it.