I think most things have already been said and done to death but I just wanted to chip in.
I'll happily pay £10 a year or another lump of £30, more than happy to do so. The historic threads, knowledge on here and all the information available make that a bargain.
I'm an 'online only' member as meets aren't generally my thing, takes a lot of effort just to be bothered to go to local ones, but the forum is valuable for the resources and as a way of keeping a log of the car (build threads.)
There are definitely some cliques and there are also a couple of bad eggs (both new and much older) but I guess thats par for the course for online forums.
I do think forums as a whole are in decline, there are the hardcore few who won't use other forms of social media but the fact is that Facebook, Instagram and the like are killing forums and that wont change.
Like I said though for the simple fact of being able to search for a thread someone created 5 years ago detailing how they did a particular job, this place is still very useful.