In Stephen Schneider's defence, that quote comes from an interview in which he was lamenting the media's coverage of science, and how to get media attention it is necessary to provide a juicy soundbyte.
I don't think he was encouraging people "to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have", rather lamenting that this was all that gets reported.
He goes on in the interview to say that the best way to get the point across without overstating it is to "use metaphors that succinctly convey both urgency and uncertainty".
In any case, while you can get away with exaggeration, over-simplification and deceit in mass media, you cannot get away with it in peer-reviewed scientific journals.
