I disagree, Tomcat. One point of a game system is to emulate, as best of possible, the feel of the characters of the universe in which it takes place. In this case, Starfleet characters have a broad range of knowledge, so skills are broad by nature, and specialties simply add to their test result.
What you're suggesting is to change knowledge skills to make them different from every other skill in the game. Instead of a broad skill like "Knowledge of Cultures" (which would be similar in scope to a broad skill of "Propulsion Engineering"), you're saying that a character should only have "Knowledge of Earth Cultures." That would be like "23rd Century Starfleet Impulse Drive Engineering." It goes against the principle of broad knowledge and skill that is inherent to the Star Trek universe.
Davy Jones
"Frightened? My dear, you are looking at a man who has laughed in the face of death, sneered at doom, and chuckled at catastrophe! I was petrified."
-- The Wizard of Oz