You're overlooking a few details - not least of which what azbill mentioned lol
This site is growing by leaps and bounds, slowing only during the off seasons such as fall and winter and while requested by members the additional subforums were also provided to help "clear the muddy waters" you complain of. With so many new members joining all the time it was becoming exponentially more and more difficult for members to find the information they're looking for, it was in fact somewhat chaotic. These subforums are also quite new, we only recently added & populated them by moving existing threads - which may have given the false impression of infrequent use. We do suffer a bit from duplicate threads, those members that in their haste don't use the native or custom google search engines, but we've decided to not curtail that as often it's the newer members seeking help - and that's one of our primary interests, helping the new member as much as we're able. Actually I believe the addition of specific subforums has greatly reduced the number of redundant new threads by providing an obvious source for the answers they seek.
"...and have them kept as ONLY technical discussion, no socializing"
That goes against the general wishes of the administration concerning this forum and actually what I personally think forums are for - general socialization. While it's true some forums enforce a strict "on topic" policy and in some ways that does provide some benefit, not only are we loathe to be that strict here - in my personal opinion I've realized it not only drives away the new member perhaps unfamiliar with general forum etiquette, it actually also hinders far more than helps in the long run, which of course depends entirely what you're after.
If your a non-bot guest (of which I assure you are more common than you think) after nothing but information to read & leave or you're a member wishing to display your work & little more, such enforcement does in fact serve to keep the topics "pure" - yet I've noticed if free to converse & discuss whatever tangent they're interested in, oftentimes far more information is provided that just what was outlined in the OP - not to mention "provide(ing) continuity and promote(ing) unity" by not restricting aspects of social interaction. We strive to provide a far more relaxed atmosphere here, welcoming to the newcomer and with as
few rules as possible:
http://motorbicycling.com/f21/please-read-these-simple-rules-2.html and while we do ask that topics & discussion be at least somewhat bicycle related as we are a motorized bicycle forum after all, pretty much the only "taboo" subjects are of course the nefarious 'Politics & Religion' - to be avoided at all costs lol
Which brings us to
vBulletin which is yet again personal preference, while the company itself has been around for at least ten years, I assure you the software has undergone a bit of revision since then lol and is in fact one of the most popular forum platforms, particularly for sites more interested in content than glamor. Actually with it's near infinite number of plugins and user-defined modifications we're able to provide as much "glitz & glam" as other platforms yet choose not to as such frivolousness only negatively impacts load times. If anything the stark simplicity allows us to focus on the truly important - content, while also providing unprecedented software stability.
The aforementioned restrictions are in fact in place not as a limitation of the software, but to reduce server load and page load times for our members BTW as again, vBulletin is almost infinitely customizable.
Yet you're right - this site does need some work and hopefully always will as any site undergoing such growth will need constant revision and tweaking. In fact our administration works on this site on a near daily basis, while much of it obviously goes unnoticed by the memberbase save the most profound changes like the addition of subforums, the staff is constantly working to provide the best platform possible for our members and their projects, based on our observations as well as viable suggestions from members.
If this site was static, limited in growth and members your suggestions and observations would be accurate and appropriate so I thank you for them, fortunately it's quite the opposite and as such we've a whole different slew of issues to contend with, of which I'm quite happy to report are relatively minor and have actually mostly resolved with the addition of said subforums