dont let people be conspirators if they have the pref off

[Avack]

I haven't been on 1 that long, but is it a safe presumption that antags tend to be the main conflict causers?

No. That's Tooty.
 In all seriousness: RP1 already gets a whole load of extended rounds and rounds where the antagonists stay out of the way / don't know what to do / didn't want to be an antagonist in the first place. I think one reason for this is that forcing people who don't want to be antags into the role just means they often won't do it! Here's what I'd suggest:

• Roundtypes which rely on roundstart antagonists and relatively high population counts remain the same as current. Examples: Nuke, blob, rev, gang. None of these appear on RP1 anyway, so there's basically guaranteed to be enough people.
  
• Roundtypes which don't, however, such as traitor and changeling, get changed so that antagonist preferences are totally respected in the case of roundstart and latejoin. They can therefore start with no antagonists,  but until at least one antagonist has been chosen the chance for latejoin antagonists to appear is greatly increased.
  

 This means only people who are willing to do it will become antagonist and near-ensures there will be at least one antagonist. Seems better to me than the current setup.