I can honestly tell you, that apart from knowing there had to be something CGI involved (most of the time, not all sketches did in the end and I'm guilty of that more than most) everyone I know just wrote stuff they found funny.
Although I suppose you could be right in a way - for me, the concept of the sketch comes first and I fill in the dialogue later. On the other hand, the concept usually makes me laugh so ... don't know really.
I can categorically state there was no cynicism behind it - it's just people trying to make a show they would want to watch.
