There might be some sort of cognitive bias going on here. But, I think the greater driver is more "political."

Complexity creates opportunities for fiefs, little areas only one person understands.

I think we don't recognize what drives a good portion of people, in the tech industry. People pretend to, and are often expected to understand more than they do. Complexity helps us when reporting or manage (up and down). It's harder to grill you, challenge you or commit you to things when everything is complex. Complex requires more people, which is the main scorecard for corporate success.

It's also just unintuitive that simple is harder and better than complicated. Even if you get it, someone else won't.