I agree with your assessment. The amount of space for the baboons is quite large, but the lack of shade, lack of water, lack of substrate, etc, all make it a disappointing exhibit. This baboon island is almost right next door to the enormous Tropic World, another mostly fake set of habitats.
I think that the worst part of the entire exhibit is the lack of shade. The day that I was there it was scorching hot, and all of the baboons were jammed into the tiny areas where they could find shade. The zoo should at least build some type of housing structure or elevated platform with a roof.
Brookfield zoo knows that this exhibits are out dated but are trying to make othe improvements before this area is improved. This is what the stratigic plan said "Refresh exhibits that are outdated and in need of deferred maintenance,
increased animals, and improved guest experience—examples are Perching Bird,
Baboon Island, Bear Grottos, Pachyderm, and Big Cats" And it said that this will become a japanese macaque exhibit. My guess to why they are changeing species is because they can leave the macaques out in the winter.
When i studied in Chicago i enjoyed watching the guinea baboons here, they were very active. There is already a very nice japanese macaque exhibit nearby at the Milwaukee zoo. The large baboon troop at brookfield was studied by various researchers and will be missed when they leave.