Battle of Britain days are a relic from the past and rightly so, we tend to lean on our laurels a little too often imo. We should be grateful that the BBMF exist as a reminder of those days. I'm with the OP in that displays are not as entertaining to the general public as they were, where I can still appreciate the precision and skill in a display, many can't and want to see it up close and personal. Remembering displays from days past, North Weald springs to mind and the glorious cacophony of hundreds of car alarms objecting to 4 olympus at full chat as a Vulcan displayed (beautifully), a german registered visitor not reading his Notams and arriving in the middle of the BBMF display (the irony), Mark Hanna flying under a spit in a P-40 with his prop tips about 2 feet off the runway and various WWII fighters in formation with a (Northwest?) B747.
As regards the use of training aircraft by the Reds, most folk just see it as an RAF jet.
As regards Shoreham, an avoidable tragedy yes, but in the present safety above all else climate, the outcome wasn't a surprise, also remember that Ramstein was also a game changer in its day, modern jets not classics.