Is this a problem prevalent in computer science generally, moreso than other disciplines? Lots of companies, for example, think they can write their fancy software suite in six months, without designing it in detail first, and still be working on it five years later. OTOH, the physicists, chemists, and in some cases engineers seem to have no problem saying "we have no idea how this phenomena works. It's going to take a lot of people and a lot of time and a lot of money to develop understanding and control of the process." That, of course, could just be a side effect being graded on publications and grants rather than products, but it's still suggestive.