The appeal of bad ideas -- why do rational executives keep trying ideas that never work?

A while back my friend Brian (of Ultrasonic Remote) and I found ourselves on the subject of TV remakes, shows that kept the title and general premise of an old hit but rebooted it with a new cast. After a while a pattern became obvious, the few successes all had something in common: they were all science fiction or fantasy shows (and even there the odds were not good).

When we went out of that subgenre, we couldn't come up with a single success. Many of the shows were high profile affairs with talented casts (Kojak, Dragnet, the Fugitive) but we are still talking about a failure rate of pretty much 100%.

Eventually, some show will break the streak. Perhaps it will be Hawaii Five-O or the new Rockford Files (after all, how hard could it be to replace James Garner?), but this still begs the question, why do highly paid executives in a tremendously competitive field insist on trying things that have repeatedly and consistently failed?