Well, you're kind of out of luck. If the functionality exists on the wiki then it can be applied on any basis, or on any page that someone wants to use it. Just like the random flag allows not only the random screenies on the front page but also the application of, for example, a random mods section on the modding portal, or a random campaign-specific screenshot on the page of a given campaign, a rating bar applied to mods can't be limited by any system I know of to just mods.
If someone chooses to put one on their campaign page there's nothing anyone can do about it, and there's nothing anyone should want to do about it. After all, while the wiki as a whole is collaborative, it's really up to the individual campaign authors how they choose to display their campaigns.
What's not going to be happening, given expressed community opinion, will be the applying of the rating bar to all campaign pages. Realistically, the likelihood is that only a relatively small number of people will choose to use it - it'll only become a problem for those not utilizing this feature if a significant majority of campaign pages chucked one up, which, if this poll is accurate, is highly unlikely.