I think that's a false dichotomy. The good carpenters I know are all reasonably good designers. And I would never hire an architect who didn't have some experience actually making things; otherwise there's too much risk of getting what software people call "architecture astronauts".
I think the right solution is the approach IDEO takes: teams of what they call T-shaped people: broad general understanding, with great depth in a particular area.
In Facebook's case in particular, I don't think they need a lot of brilliant design as much as they need solid, competent, well-integrated features. Indeed, their latest attempt at design brilliance, Timeline, has been much less well executed than their zillion engineer-led evolutionary changes.
The IDEO approach is something that I like and look for in the people I work with. When I was teaching I grad school, I'd often exhort my students to think at least one level 'above' and one level 'below' whatever phenomena we were studying that week.
With software, I think it's important to see the forest for the trees, so that you can make the best tree for the forest... (apologies for the tortured analogy)
I think the right solution is the approach IDEO takes: teams of what they call T-shaped people: broad general understanding, with great depth in a particular area.
In Facebook's case in particular, I don't think they need a lot of brilliant design as much as they need solid, competent, well-integrated features. Indeed, their latest attempt at design brilliance, Timeline, has been much less well executed than their zillion engineer-led evolutionary changes.