There I cited one such reason without thinking 5 minutes

http://lesswrong.com/lw/9sv/diseased_disciplines_the_strange_case_of_the/5tz7

Actually, the same bug being found earlier rather than later will probably be cheaper to fix, the question about measure of that cheapness (and whether the difference always covers the cost of finding it earlier) is impossible to answer with current level of actual expense we as society are prepared to spend.