1) They're hired to watch the disaster not participate in it.
2) They're not equipped for it (depending on the aircraft there might be video production and transmission equipment in the back instead of seats)
3) For lack of a better term "it's not their job".
4) Why don't military aircraft do the news reporting?
5) From a personal standpoint, if they're (whoever owns/charters the plane) not paying for it and it's not a matter of immdeiate life and death (not sure how floods work in Australia but when they hit in the US the water recedes with time) I'm not getting involved in anything more than I've been asked to do.