Definitely this. I'd had it hammered into me that I need to understand the business to be a good dev, and it's true. That domain knowledge is essential to do a decent job, or even do the job at all.

Rhe reciprocity, though, is mostly missing. An attempt to understand the IT side is essential for managers but most often they can't be bothered (or bothered to understand the principles of user interfaces, for that matter, anything that falls outside their domain). The few bosses I have had that did try were very good to work for indeed, but such are rare.