That's a complex question for which I don't have a simple or brief answer.
In general, we all have tons of biases and most of us aren't even all that aware of most of them. People tend to identify biases revolving around ethnicity, religion, gender, sexuality as bad biases. But even that's oversimplified because there are negative and positive biases (e.g. someone who loves natural blonde hair).
So I'll hypothesize that insofar as any type of bias might artificially narrow our thinking on a particular subject, that's bad if the goal of our thinking is to reach an objectively, provably, deterministic answer.
I say hypothesize because I'm not sure that's right or not. But it seems like it could be.