IMO, all the question with subjective tone should be flagged as subjective.
It would make easier to filter questions when one want to answer subjective or non-subjective questions.
Do we need subjective questions at all? What is the purpose of them? Stackexchange is not a blog, not a forum, and not an online book. It's a Q&A site, where I ask a question and get an answer. My purpose is not "to talk" here, but to get or give information.