That's where we get the problem. That IS a debate, because you're leaving subjective preference as soon as you think there's anything OTHER than subjective preference at work - which is the case by definition if you provide reasoning, something that subjective preference is not subject to. You don't need reasoned justifications for "I don't like X". And I really mean reasoned justification, not just more layers of preference, i.e. "I don't like chocolate, because I hate the taste" is not reasoned justification, it's just more subjective preference. As would be the case for something like "I don't like chocolate because it tastes like ash and dust" since that's purely subjective, too.
If all you're doing is elaborate on a subjective preference, that's fine. Debate begins as soon as you bring in reasoned justification and (implicitly or explicitly) try to convince other people of the validity of your position.
That's my point - it's NOT just an opinion anymore as soon as you use it to try and convince someone. If you're saying it's bad because aliens told you so and you read about it in the Bible code... that's cool as long as you purely use that in the sense of subjective preference. As soon as you expect other people TO BELIEVE THAT REASONING, we've left opinion and entered argument. Whether you like it or not.
The whole problem I'm pointing out is that people very much want to blur these lines, because it allows to PRETEND to have an argument using their OPINONS, which gives them the same persuasive power an argument has, but allows them to dodge epistemological responsibility by claiming the immunity to reasoned justification that governs opinions. You can't do that.