This was meant to be a comment, but it is simply too long, so I'll pretty up the formatting as well, why not...:
...becoming what it's aspiring to be? -- what's it aspiring to be? Who dictates that? The SE staff? The users? Both? Being tech based, are their real numbers/data/analytics to support or refute those aspirations?
The tour page states:
With your help, we're working together to build a library of detailed
answers to every question about professional server, networking, or
related infrastructure administration
...so I guess that's the aspiration, in all its vague glory. I've heard other mention here on Meta about the original intent of the site as well as what users in general want it to be, but unless it is spelled out on the first page people see when first visiting like above then it doesn't count as the actual intent, does it?
But is the site actually failing? I think we have a few different viewpoints:
The High Reppers
These folks are extremely knowledgeable in their fields, like answering questions and helping others, and are most often daily users of the site. They might hang out in the Comms Room, be mods, or maybe just like answering questions. They have nothing to prove at this point and "rep" holds no real incentive for them.
IMO, they see the site as a place that could be THE PLACE to get your real sysadmin questions answered without going to the vendor for TAC support and possibly getting a better answer than the vendor could provide because of the rounded and expert knowledge in the field. However, some if not most are becoming more and more turned off by the lowbrow questions and drive-by users that come from SO/SE or the web to simply ask questions about the "blue collar IT stuff" so that they can get back to to the really important stuff.
These are the folks that could be making this site attractive to the outsiders, by showcasing their profiles, marketing their knowledge on the site to let new users know who they might get answers from, etc.
They tend to like the Regulars overall, are ok with the Every Now and Thens, and are very hit or miss (often miss) on the Noobs.
These are the folks that keep coming back and may eventually be High Reppers. They are experts, but may not have been here for very long or have grown weary of answering a lot of questions just for "rep". You may seem them as well in the Comms Room, review queue, or contributing in Meta.
These people need to be retained...SF has hooked them, but how does it keep them engaged on ongoing basis? It's much easier to keep a customer than get a new one, so why not put some effort into these folks?
The Regulars tend to like the High Reppers, and are OK with the Every Now and Thens. They see the Noobs as hit or miss, and some are active at VTCing/voting/Review enough to help the High Reppers with site cleanup.
The Every Now and Thens
These folks like SF for it's Q&A style, but could take or leave the site. They come when they have an issue or when they're bored. Their rep can be all over the board, but they are definitely not daily or even weekly users. They could have been at one point and got bored or frustrated by the site, or they simply never saw the need to be here regularly.
These folks have the potential to be regulars...I'd venture that most IT folk WANT to be a part of a strong IT community...but they may see SF as nothing more than a simple place to ask a question, not a "community" of IT pros.
However, this group also lumps in the SO folks and other SE site users that tend to drop into SF on occasion to ask a sysadmin type question simply because they are stuck and want to get on with their project. They have no real interest in the site itself other than a quick answer and they'll be on their way.
The Every Now and Thens probably have no real opinion on any other group here...they don't care in general. However, they will get pissy if you downvote them and explain that this site isn't for non-sysadmins. They are usually the ones you'll end up seeing ranting in Meta about how sucky SF is and how it will go down in flames with the High Reppers in the building.
These are either first time visitors, fairly new folks, or drive-by users. Most will never care what the site is for or about. They simply want a quick answer to their issue. Damn the instructions, tour, FAQ, etc. I can post without signing up? Heck yeah, it's worth my 60 seconds to ask and see who bites.
The potential regulars and high reppers in this category are very few and far between. They are there and the good SF'ers can spot these folks and will upvote them and try to hook them to the site.
The noobs overall don't care about any of the other groups. Some are vocal enough to give attitude when downvoted, while most could probably care less...since they were simply hoping a free site and 60 seconds of their time would answer their question without them having to research or hire a pro. They don't have enough rep to really contribute to the site, nor do they really care to.
Great, you listed out "classes"...what does that have to do with site vision/aspiration?
I think knowing your audience groups and knowing who you want to attract/retain is important. I also think your audience should know what to expect from you. SF does a pretty decent job overall of letting its users dictate how the site should flow. It's not really a few folks controlling the site, but through votes/etc. the users overall through "mob mentality" and majority tend to self-govern pretty well.
But SF lacks in being able to showcase the talent it really has on the site. Why not put something in the tour that showcases 3-5 of the high rep users, what their background is, and what their expertise is? Why not create a "blank" one with a "this could be you" as well to let others know they could get their name in lights someday here? Not everyone would want this, I understand, but it's an idea of how to attract/retain folks.
I think that's enough...I'd keep going but I doubt anyone has read all of this to begin with...so I'll digress at this point.