Seeing genitals invokes a state of arousal in a lot of people. The fact that covering genitals is a social standard in nearly every culture indicates that this is a normal response.
Some cultures, including western culture, even sexualize tiddies. Contrary to what some people suggest, there is nothing wrong with having that social standard.
If nudity became more socially acceptable, the people embracing that freedom would be the EXACT people you wouldn't want to see embracing that freedom. Furthermore, it's really unsanitary. Imagine sitting in a chair that had some sweaty guy's unwiped anus rubbing against it 30 minutes earlier.
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http://www.youtube.com/watch?v=XiCtAUrZbUk
-- Defeating the Running Man of Ocarina of Time in a race since 01/17/2009. --