I haven't actually spoken to a lot of people about their philosophy of time, but my best guess for why one would develop a strong emotion on the topic is that when one first encounters the distinction, one identifies one of the theories as "common sense" and the other as "counterintuitive philosophy", and they have a strong emotional disposition one way or the other regarding that dichotomy.

(I'm not sure there's a general answer to which theory is common sense, but I think it's likely one would make an identification one way or the other)