Paper accepted subject to minor changes – should I comply if I do not consider them minor?

Whether you should comply or not should be ruled by asking yourself if doing so will improve your work. If you come to the conclusion that it would improve the paper, you really should follow the advice. Most other considerations such as if it is a lot of work should be very low (if at all) on your list.

As a self-confident researcher the quality of your work should be in your focus. It is therefore never mandatory to follow reviewer advice, but it is mandatory to explain the reasons if you decide against it. If there are good reasons not to do as requested, you can explain it accordingly to the editor. In any case, the editor is the one to convince, so you could discuss your question with her/him.

Rule of thumb number 1 for replying to referees: Never say "no" if it can be avoided. If I had your case, I would include a discussion (a few lines) of the inclusion of said parameter, and highlight it as a topic for a future article. Then I would thank the referee profusely for giving this suggestion, that it would be a challenging thing to do, and that this is something I would consider further in the future. Given that the paper is already accepted with minor changes, I would not expect the referee to push back on this.

From the sounds of it your paper is not accepted, the referee has recommended acceptance but the editor must finally accept it before it's formally accepeted (at which point the only changes allowed would be formtting issues and typos). As you have minor edits it maybe the referee thinks the changes are small and thus may not want to read the paper again, in which case you only need to convince the editor that the work is not minor. They can then decided whether to ask the referee (or not) for thier opinion on whether to accept without the changes.