It seems to me that the awareness of the readers is always necessarily going to be there. Even when I don't write specifically to be entertaining (and I suspect that most of my messages will be a little more mundane than I started out), the knowledge that this stuff is public is going to act as a filter on what I write. Some thoughts are simply private -- not for public consumption, no way, no how. Even if I labeled the security as nominally private, there are things I simply wouldn't post here, because I don't trust the security quite that much.

Beyond that, it's a matter of scratching your own itches. For me, the wit thing is less a constraint than an opportunity -- I don't generally get enough chance to flex those particular muscles. (And they are mental muscles, that atrophy if you don't use them enough.) But that's not everyone's cup'o'ramen...