Point 1: The taxiways to the "terminal" at Cambridge are piss poor, not wide enough and incapable of handling much more than a FK50, never mind a fully loaded B737.
Point 2: Cambridge do not have the ground/terminal staffing, training or capability to handle normal scheduled flights, Suckling with 20 or so business folk was one thing, Ryanair with 200 or so passengers in various states of coherence is entirely another.
Point 3: Marshalls, despite many years of having the opportunity, have not take advantage of the potential to attract this sort of traffic, sadly their management has let them down and it's their loss.