I think there is also a point in that as much as the RIAT Team are enthusiast friendly and will try to arrange the odd surprise and rarely seen Aircraft, they also have an obligation to make money, and that involves getting as many people through the gate as possible! I don't know what percentage of RIAT visitors are enthusiasts compared to 'joe public', but with an increasing decline in military aircraft compared to days of old, they've got to give them something for their money, whether that be hard core fighters or wing walkers!
One final point, I posted on this topic a few years back, expressing my disgust that XH558 wouldn't be attending RIAT and how it was being overrun with civilian stuff, only to have it pointed out to me that she was in fact registered 'G-***'

Just my rambling thoughts!
Steve.