The insidious thing about over engineering is that it's usually committed by very experienced engineers. Experienced engineers rarely under-engineer, that tends to be fixed very early in one's career. As we get more competent and read more books, we have the tendency to get enamored by new fancy abstractions. We get too clever and then we get in our own way. Best real-world example: I inherited a project that was an…
OP suggests there's a hump in the curve of experience vs over-engineering; more experience correlates to over-engineering until it gets to a certain point, at which even more experience leads to less over-engineering. Is it true? I don't know, I think it matches my... experience. Part of it is that the "experience" needed to avoid over-engineering is helped if it's not just engineering experience, but domain experien…
After discussing it with the customer, a simpler solution often emerges, where they change the requirements slightly allowing for a much simpler solution that might even solve the actual needs better.
While it's not just down to experience, I'd say it has a strong influence on being able to see beyond the given requirements towards a better outcome.