>One problem I see is that these types of interviews, which are essentially basic aptitude tests, might be regarded by the interviewers as far more than they really are. The idea of "preparing" for a coding interview is absurd. If the applicant feels it is neccesarry to prepare he either is completely unqualified or the testing method is bad.

I think it is because it started as just simple "weed out the weeds" questions and somebody got bright idea that "the harder brain teasers they ask the better candidates will be left", not realizing they are just recruiting people that are good at trivia.