I think most people live places where they can't live outside all the time. Plus, most people didn't know how HUGE they get to be in the first place. If you showed pictures of the size of your setup to someone who has only seen the cute little baby and they will probably have a heard time believing their little greenie will get that big.
I've known plenty people with iggies that bit, tail whipped and scratched a lot. Males can get aggressive depending on their temperment and whether it is iggy breeding season
http://www.anapsid.org/iguana/breedi...on.html#freddy
http://www.anapsid.org/iguana/season.html