Programmer and designer overlap a lot, especially in places where the programmer/designer have much experience. They are usually the first ones to nod or shake their head at some aspects of a game's design, due to possible technical/code restrictions, and should be involved in design a lot more. Artists, too, should have some input and work with the design, instead of being told to "go paint a ____..." After all, if they fully know or work with the design details, their research for the artwork is just that much more brilliant, and it shows.
That is why I liked Troika. True, each of the "three" had their personal forte, but in design a LOT of things should overlap. One of the best things I remembered about Origin would be despite the roles and titles, everyone had input into the games, to a practical limit, of course. This was most obviously seen in Ultima, where nearly every developer lent a personality to one or more characters. When they are given something like this, it instills pride into their work, and so besides their usual tasks they work to enrich the game on every point they have an input on. To me, when developers are allowed to each handle things like that, they work a bit better with each other to nail down the personalities and characters of the actors in the game.