Agile is popular in IT because our ability to estimate and plan is **** compared to real engineers. .
...IT also has the 'advantage' that you can deliver part of a project and still have something usable. Doesn't apply to real engineers: who will accept a suspension bridge without the deck, or a car consisting of the chassis, 2 wheels and an MP3...
I think the point is that IT projects are not always logical in the way most non IT people understand "logical". Also people who understand IT projects and are good managers are not that common.