I guess their status in the wild- endangered/vulnerable?- ensures they will continue to be kept in large numbers in Zoos, but I agree they are pretty ubiquitous in the UK collections- being free breeders also means they are far more commonly kept than any other Macaque species- even those still commoner in the wild like Rhesus or Bonnet.
I think for Macaques, it doesn't matter how cluttered it is- its just all the more available space they can use, either at ground level or above it, giving them effectively two levels. I think most of the comments about this are perhaps more about the aethsetic appearance- personally for me thats more of secondary importance.
I'm not clear whether they have yet got another, 2nd male group, somewhere near the entrance, as well as the male/female group under the Ski-lift. Either they have or they will have shortly.