"At the 2008 RSA security conference, Microsoft's David Cross was quoted as saying, The reason we put UAC into the platform was 'to annoy users. I'm serious.' The logic behind this statement is that it should encourage application vendors to eliminate as many unnecessary privilege escalations as possible by causing users to complain about all the UAC 'Cancel or Allow' prompts. Of course, they probably didn't expected that Microsoft would instead get most of the complaints for training users to ignore meaningless security warnings."
http://arstechnica.com/news.ars/post/20 ... y-you.html