I took a bunch of time and focused on helping coders instead of coding myself. I came to coding naturally and never thought of it as much more than intellectual self-stimulation. It was a lot of fun, and there is some value to it -- but it tends to get a lot more attention than it should simply because it feels so good to do it well. Successful startup founders say that coding is no more than 2-3% of the total effort…
It depends on their attitude. The smarter the better, IMO, as long as they understand that the code they're writing isn't for them. They can go hack on some personal project if they want to flex their "I'm so clever" muscles, but if they're writing commercial code, that code is for the dumbest of the dumb who will ever have to maintain it. If someone can focus their intellect towards making their code clear and simple then great.
Of course, as you say, someone who's competent but has a slightly humbler intellect will just automatically write simpler code.