I think Steve Irwin got close to animals to make his show more exciting and to bring his message of conservation to a wider audience.

The interview Andrew Denton did with Steve Irwin a few years ago on "Enough Rope" is a good insight into Irwin's character.

Transcript: http://www.abc.net.au/tv/enoughrope/...s/s1732743.htm
Video (part 1): http://www.abc.net.au/tv/enoughrope/...ip=steveirwin1
Other videos aren't up yet (but should be later this week)
Enough Rope website: http://www.abc.net.au/tv/enoughrope/default.htm