Experts will continue to stay away in droves, as long as we bicker amongst ourselves. To increase from 200 talented amateurs to 300, 400 or 500 people with even the sparsest sprinkling of subject matter experts, we must do something to make Wikipedia a more congenial environment. I'm not sure how to do this. I'm only sure that we must.
I'm not exactly sure of this. So-called "experts" like a good bicker as much as the rest of us. Have you ever read the letters page of an academic journal? The insults fly between the ivory towers as viciously as in the grimy bars, you know :). So don't expect so-called "experts" to be necessarily put off by argument, and also don't expect them not to indulge in it should they ever turn up :)
I agree; lively, vigorous argument is a good thing in itself, and won't drive away anyone who's worth keeping. We're not a social club here, we're producing a product, and if a little shouting helps that project, that's fine. What drives people away is when they feel they aren't contributing. If they spend more time arguing than writing, and the arguments don't actually serve to improve the articles, then they feel their time is being wasted.
So arguments here should be judged not on their belligerance, but on their productivity. Is the argument truly seeking to make a better article, or is it just arguing for the sake of argument, or to push an agenda?