Perhaps having "skins" capabilities would allow the best of both worlds...though it might end up like WinAmp with thousands of unuseably designed yet popular skins.
For example, you could decide to move some functionality from a sidebar to a context menu. this implies reprogramming the interface very differently; a skin can't do that. This also implies prototyping a lot. So basically the designer and the coder have to sit together quite a lot, that's not easy when you communicate via internet.
