How to better handle closing of opportunities?

Seasons Greetings Everyone!

I'd like to adjust how we handle closing of opportunities and really only want to make COMPETITOR a required field for when we close an opportunity as a loss.  Unfortunately, the Opp. Close form is not editable (why did you do that Microsoft!?!?) and I also can't make that field required.  

What is the best way to handle this - should I remove those options from the workflow and just add multiple stages and handle as an opportunity field?

Thanks!