Those are not "too smart" engineers. Those are "too dumb" engineers, with a will to prove that they are not that dumb to the rest of the company, or themselves.

Those are not "too smart" engineers. Those are "too dumb" engineers, with a will to prove that they are not that dumb to the rest of the company, or themselves. Explain them that complexity is their worst enemy. They won't understand. Explain them again, with more examples, real life situations where complexity wasted time, money, and even, lives. If they keep not understanding, fire them.