Proprietary formats could be a manifestation of "Not Invented Here" syndrome, which is usually an engineer's vice. Granted, it's not often a good decision, but

Proprietary formats could be a manifestation of "Not Invented Here" syndrome, which is usually an engineer's vice. Granted, it's not often a good decision, but it's one that still gets made by engineers with regularity. The usual catalyst of NIH is thinking that the standards suck and you could do better. So, as you say, it requires that decisions be made not just by engineers, but arrogant engineers, with both those words sharing part of the blame.