[RobertKerans]

With programming, generally fixes, or even say major features can be done in isolation. Programming is not, in the small, a hard or subjective task. Once the initial decisions have been carved into stone, it's relatively easy to take contributions from a wide variety of contributors.

With design, it's subjective (this is key), and benefits from a comprehensive approach by a dictator. Many small contributions from a large number of contributors is not a good thing (generally). It turns into design by committee; which in general, just generates shit. Part of this is because you can't design isolated parts, you need an overall working view and inderstanding of the entire functioning system at all times.

You can get around this with extremely strict style rules, which would allow the same type of contributor patterns as the coding side of things. But that's very rare to find, for one because it's extremely difficult to create those rules in the first place.