Actually CS comprises of around 15% of undergrads and commands a dominating influence over the rest of the school. http://stanfordvisualized.soraven.com/
I would describe 15% as a small minority. I agree that the department is important to the school (possibly the most important single department), but I think your characterization of its influence as dominating is totally incorrect. I'm guessing that you have a lot of CS major friends, live with many CS majors, and probably study it yourself. However, there are plenty of places on campus which have almost no influence from the department. Examples which immediately come to mind are the co-op I lived in last year which had 2 CS majors out of 56 residents, the several-billion-dollar medical school, and the school of humanities (which in aggregate dwarfs the CS department in terms of enrollment). Even the rest of the School of Engineering isn't really influenced by departmental decisions. I think that most members of these communities would strongly disagree about being dominated by the department; your perspective likely stems from sampling bias in some regard.