It's probably not unethical. (Note: Don't infer this answer to mean it's good. Or bad.)
At the risk of pointing out the obvious that no one else desires to, grades serve 2 roles:
To evaluate how well the student has already mastered the material.
To predict how well the student is likely to learn and apply such material in the future.
Giving everyone an A indicates that every student learned what the instructor was trying to teach, but does not at all indicate whether two students from that class will perform similarly if faced with different (but related) problems in the future.
Similarly, forcing the lowest grade to an F and the highest grade to an A fixes the second problem, but does not at all indicate whether the students in fact learned the material that was taught.
So, basically, what we have here is a "multi-objective optimization problem", which generally implies there is a trade-off and no single mathematically optimal answer.
(You'd think we could give 2 separate numbers for these 2 things rather than just 1 number, but the real world probably isn't very open to this idea.)
This means it is at the instructor's/department's/school's discretion to figure out how to combine these 2 measures into 1 measure, and that is something students must fundamentally accept. So your notion of being "ethical" must hinge on more than merely you disliking where the professor struck the balance between these two objectives.
So now we get to the particulars of your situation, which boil down to this quote:
I'm losing points for things I didn't before, and being asked for additional analysis that has never been required.
If I understand this correctly, this means one of the following:
You were marked down for not performing analysis that were not required.
You did analysis that were not required, and were marked down for mistakes in those.
Unless the analyses were blatantly off-topic (such as analyzing Shakespeare's plays after solving your linear circuits, which I assume they were not), in the first scenario, what has happened is that you have done less thorough and/or less correct work compared to your peers, and your professor has deemed it necessary for this to be reflected in your grade. Presumably this has happened either because he thinks it is a likely indicator that you didn't understand the material as well (reason #1), or that it is a likely indicator that you would not be as correct or as thorough about such material in the future (reason #2).
In any case, I hope you can see that there is nothing unethical about this behavior. It is clearly a judgment call, but it was quite clearly done in good faith and completely within his discretion and responsibilities as an instructor. You're welcome to claim that it is a poor judgment call and complain based on that, but I see no evidence for the claim that it is unethical.