Ethnocentrism is border-line racism. Ethnocentricity can actually turn into racism. The line between pride and hate is too thin for most people (because most people are complete idiots). Saying "my culture is better than yours" goes entirely against "I had a dream, that all people should be equal" (to borrow a quote)..... Yes, people should have the right to be stupid and ignorant, however, stupidity and ignorance should not be allowed to get in the way of making informed, intelligent, and fair, humane decisions as a society or community.
Put it this way, "ethnocentrism" was tied into nationalism and pride became hate, and we ended up with NAZI Germany.