It's OK to not like things. It's OK for other people to not like things. It's OK to like things It's OK for other people to like things. These are four separate categories. It's important to understand that preferences are just that... preferences.
But I really do think that there is an urge to not be "mean" or "unfair" or "negative" that is making us grope for rationalizations for why it is not just Correct but Righteous to dislike this person. (or book. or tv show. or or or) And it's actually okay to just... not like things.