While I agree with your sentiment, there is a difference between not understanding and actively disparaging. The former is fine - there's plenty of stuff I don't understand, and I just don't comment on it because I have no business doing so. Where I take objection is when the lack of understanding transforms into bigotry and disparaging remarks.

By all means be ignorant (and I don't mean that in a derogatory manner - we are all ignorant about various things), but don't let your ignorance manifest into negativity.