I play Server Fault for fun, and because I like how it feels when I actually help somebody. I'm sure that some people do play to forward their "religious" agenda w/ respect to IT, but I think they're fewer in number than your question suggests.
I hope that, above all else, the Server Fault community works to keep the site fun and welcoming. Having a reputation of being insular and unfriendly is worse, to my mind, than having a reputation for being inaccurate or unhelpful. Frankly, we'll never get a chance to be helpful to anyone if our collective attitude intimidates questioners. Running the site in the ground while trying too hard to keep "on topic" would be a real shame, and something that I think that all of us who enjoy Server Fault need to keep in mind.
All-in-all, I see the Server Fault community as being very knowledgeable, though sometimes "focused" perhaps a bit too finely on the intended subject area of the web site. I didn't vote to close the health-related question earlier today because I agree that the typical "all consuming" occupation that is systems administration can lead to a sedentary lifestyle and being overweight. I'm also alright if the community doesn't want to discuss it, though, too. I'm not going to get hung up bickering about whether the question is "valid" for the site or not. I don't happen to feel strongly enough to vote to re-open, but if enough people do it'll come back.
To speak to some of your specific points:
Server Fault is a microcosm of the real IT world. I've noticed that there's an "enterprisey" bent to the types of answers that come up on Server Fault, but that doesn't surprise me. I think that some people suffer from the "All I have is a hammer" problem when they look at solving IT problems. They know a particular tool, operating system, management methodology, etc, and look to apply it to every problem. Every IT crew that I've ever contracted with has been this way, and part of the fun and challenge in working on a contract is to learn something new and to teach someone else something new at the same time.
I do get the feeling, sometimes, that posters don't have any concept for what their proposed solutions would actually cost. Not every server role needs five 9's of uptime. Not every business is "enterprise" in its needs for change control and operational documentation.
I happen to suffer from the curse of trying to do anything I can to get away "on the cheap". It's as bad as the curse of trying to make everything "enterprisey", and I Work hard to keep it in check. I try to recognize when not throwing money at a problem ends up making the "solution" more costly in the long run.
In the end, we all need to remember that decisions about IT, in business, are about ROI, risk tolerance, and the all mighty "bottom line". No business (that wants to stay in business, at least) "does IT" for the sake of "doing IT". The "enterprisey-ness" of a given IT solution needs to be based on real business need. It should not be based on the personal whim of a sysadmin who really likes SAN gear and thinks that everything needs to be on dedicated RAID-10 arrays (or, conversely, the sysadmin who thinks that backups are for wimps and uses whitebox PCs as 'servers').
re: questions being closed to diverted to superuser.com - I do vote to migrate questions that aren't sysadmin related. If you're talking about a BIOS update on a fleet of PCs that's one thing, but questions with a scope of a single client computer aren't "sysadmin-related" to me. I don't play on superuser.com, but plenty of other people do and there will be answers posted for the migrated questions from that community. I don't feel bad about voting to migrate a question, and I don't think anybody else should either.