I believe it comes down to whether or not scientists/engineers/etc would actually like to hold office. Truly passionate people want and need to be on the ground. Becoming a leader removes one from the processes that have a direct impact.
Most scientists/engineers/etc I know (including myself) would love to hold office, but have little interest in the life-consuming activity of running for office.
http://en.wikipedia.org/wiki/Technocracy
I believe it comes down to whether or not scientists/engineers/etc would actually like to hold office. Truly passionate people want and need to be on the ground. Becoming a leader removes one from the processes that have a direct impact.