but I have also heard that not having a webcast may bring fans to actually watch the show.
That's flawed reasoning. First, 99%+ of the people who would watch the webcast worldwide either wouldn't or couldn't go see the live show in Atlantic City. Second, even for those few who were local, usually if you're the type who goes to live bodybuilding shows, you're gonna go, webcast or no webcast.
However, various fees of having a webcast also come up, like line feed, costs to have a video run live, and other costs from the actual contest place. It all depends who picks up all of these costs, and it it is worth it.
Not a valid argument, since BB.com offered to pick up 100% of the costs.