I think this has as much to do with personality types than anything else. I state this as someone married to a scientist/professor, and works with many engineer/scientists as well as marketing/business people. I think that if you *generally* look a typical scientist you will see that most scientist types will tend to be more introverted, focused, analytical, singularly driven, etc. *Generally* not the greatest communicators and salesmen. There are certainly exceptions to this, but I believe many of the traits that lend people to be very good scientists don't always lend to what tends to get people elected. If you look at the percentage of poiticians, you tend to have people with career backgrounds in which charisma is a main component (business, religious, lawyers, etc.)