You've made the mistake of thinking only of what makes a sim good for you. Do you really thin that if you were trying to convince a non simmer to give it a go, that you saying that "the campaign is brilliantly dynamic- don't worry too much what it looks like or how realistic it feels to fly the plane, or even if you can shoot something down! - just think of the campaign and how you can change the outcome of a battle etc" ??
We are talking about introducing newbies to sims --- and keeping their attention long enough to eventually think of campaigns, dynamic or otherwise.
Sigh - yes, I'm "making the mistake of thinking only of what makes a sim good for you", whereas you have a glimpse into the mind of every potential entrant into flight sims out there. Faced with such a handicap it seems foolish of me to have the temerity to diagree with you, but what the hell.
How do you imagine your newbie gets a feel for how realistically a plane flies? Let alone a WWI plane flown in a combat manner? He probably hasn't flown a plane; he all but certainly hasn't flown a plane to the edge of the envelope (I think getting your pilots license you don't bank beyond 30 degrees?); the chances of him having flown a plane comparable to a WWI plane are vanishingly small. Every mainstream review of a sim I've read has had a paragraph saying something along the lines of "of course I've no idea how realistic the flight models are, but they say they are very realistic and it feels OK". Never read one complain about the flight model. That's because they are being written by people you would call newbies.
And if we're seriously talking about really expanding the community then I'm also assuming that our newbie isn't a WWI aviation nut. He's familiar with Snoopy, maybe; seen the Blue Max, perhaps read some Biggles. Heard of the Red Baron and knows he flew a triplane. Made the odd Aerofix model as a child if he's over 25. Fancies pretending to be one of those Knights of the Sky in a game. So he just doesn't know if the rate of fire is accurate, or whether the guage is in the right place, or when such and such a plane entered service.
However, there is a form of realism that everyone, newbie or not, is in a position to understand. If I shoot at my own side, I don't need to know much to understand the realistic consequences. If I fly at 50 feet deep into enemy territory, I have a pretty good idea that I ought to be in trouble. If I bomb a stone bridge I'm pretty sure it shouldn't be rebuilt tomorrow. If I die I probably shouldn't be able to resurrect myself and try again; and if I start a new career it seems unlikely that on flying the first mission exactly the same enemy should appear from exactly the same spot at exactly the same point in the mission, and boring if they keep on doing it.
You have a point about difficulty, but here we have a major issue - because frankly if you have a realistic sim the learning curve is going to be too steep for a newbie. Even in WWI they got a significant training period and 15 hours solo before being chucked out there. You think your newbie is going to sit there through anything like that? Realism is a huge barrier to uptake in flight sims.
So once you've made it unrealistic in order to keep your newbie enjoying himself, it's going to be all about his experience in the game - how far it allows him to immerse himself in pretending to be a WWI pilot given his ignorance. Because that's why most people play games - to pretend they are something they aren't.