I don't think passion is imperative for any debate, God knows I can only rouse so much fire in me over stuff like "what is the correct mental state to properly use a website".
However, I also don't believe it's possible to approach a debate website such as this one with indifference. It's structured, for the most part, so that you must chose either on side or another on any given issue. I don't see how indifference can possible be exercised in this environment.
TL;DR: Indifference on DDO would be like something having stopped living without being dead.
Often on DDO there will be things that really irritate you, but like anywhere on the web you need to realize there are multiple trolls (I have even trolled, everyone does) and they are here to mess with you. When someone says something inflammatory or changes a vote for a silly reason, just breathe and in the words of Elsa "Let it go". Winning is not everything, ideas are way more important.
Indifference actually begets anger. If you want to stay happy in any debating forum you need to feel a passion for the things you talk about and to at times be roused to emotional outbursts though hopefully not necessarily negative or violent ones. The reason is because when you settle into indifference you become mechanical and begin to wave off people's reasoning for their logic and while the two shouldn't necessarily be separate they often are. Indifference prevents you from reading what is being said versus what is being written and judging people based on not their implied meanings but their literal meanings.
This just makes everyone unhappy.