Because we couldn't let the Americans hog all the Creationist crazy:
"This will speak very much to children... they'll hear the creak of the wood, smell the smell of the dung."
Johan Huibers
"Johan's Ark is a fifth of the size of Noah's and will carry farmyard animals."
It should be able to carry one fifth of all species on Earth, though.
http://news.bbc.co.uk/1/hi/world/europe/4853890.stm Watch the video at his site:
http://www.arkvannoach.com/