Thought I'd offer a pro UWS viewpoint here
A lot of the UWS courses are better than courses in the GO8 unis, because it's more practical based, while the more traditional unis may be based more on theory. UWS courses are not bad, as mentioned before, it's a demand thing.
I get the impression that there are lecturers who teach at two different unis, more money I guess. The big unis also have more old and distinguished professors, doctors, lecturers etc, who have published widely in their field etc. Ok generalising here, but sometimes they can get really boring, and they might be less inclined to change the way they teach because they;ve been doing it for so many years.
I think UWS receives less funding from the Government, because it's more teaching based and not research. Or maybe that's just if the new reforms go through. Either way, the older unis might have rich alumni who leave large lumps of money to the uni.
Location affects demand, perhaps this is a snobbery thing. Non Westies like to think that the West is unsafe, that crime rates escalates and that primary school kids deal drugs in the West. In reality, it's quite a safe place, people often just generalise the west based on a few snippets of "War on Crime" media reports.
UWS is less reputable than the major unis, that also affects demand. There is still the "damn I'm at UWS" sentiment. Reputation comes from time, graduates, money, research and sandstone buildings.
Graduates from UWS are generally more satisfied at the end of their degree than at big unis.