In my experience, non-engineers, tend to like simplicity.
I have learned that there's a lot more non-engineers, than engineers. Many of them, have a lot of money, that they are willing to spend on things that are simple.
Working with graphic and interaction designers has taught me to suppress my resistance to making things simpler.
Engineers thrown piecemeal at the edges of a problem will generate complexity. Engineers thrown into a room with a vision for what needs to be built and time to work out an elegant solution will get you to the moon with a pocket calculator.
If an engineer designs something, it tends to be complex, regardless of whether or not the designer has “the big picture,” because they design the whole thing to fit their worldview. Engineers have a complex worldview.
If a UI designer designs it, the chances of it being simple (from a user PoV), is much greater.
Designing a simple UI, in my experience, is often “un-simple,” however. I remember writing a visual cropping algorithm, for a film scanner.
It was a pretty damn hairy library (it ended up being an entire subsystem).
Worked well, though, once I refined and debugged it.
You're thinking like a UI designer that's watched engineers without UI design experience try to design a UI. You're referencing a lack of expertise and experience, not some inherent trait in engineering.