Beyond the wow factor, I can't really see how this type of demonstration flying helps to sell airliners. Military airplanes, I see, airliners, I don't. Is an airline exec sitting in an airshow chalet watching that, and thinking to himself: "My passengers would be really pleased if my airline could offer them that service!". I think not.
I think that airplane manufacturers do themselves a dis service by permitting [encouraging] this type of flying at airshows. I know that my friend, a demo pilot for a large airplane manufacturer, had to answer some very awkward questions asked by the AAIB in respect of the crash for which he was PIC. He had to explain why he was flying an airplane during an airshow outside its operating limitations, though following instruction provided to him by his boss, that that was what was to be flown. By the way, his boss was flying another of the company's demonstrator planes at the same time, and just didn't have the accident, but was also exceeding the limitations for dramatic effect.
It puts pilots in a really difficult position when they understand an instruction to fly outside the airplane's limits for airshow/sales demonstration reasons. If it were a formal design approval flight test, there would be a risk/benefit analysis before the flight. I wonder how that analysis looks for an airshow.
A session I participated in during flight test training discussed exactly this: You, as a test pilot, with the most experience on the new type, will be asked to demonstrate it at airshows. It's up to you to do that safely, and fly within limits. Manufacturers should respect that, and encourage demonstration flying which at least appears compliant - particularly Boeing, with pitch up maneuvers!