A bad show is different to saying stupid things and causing a loss of confidence in your system. Miss steps are ok, Miyamoto's head wasnt called for over Wii Music E3 for instance.
Remember e3 2004? Despite a losing streak Reggie didn't come on stage saying "what's the point? Great games wont change our fate".. He did the opposite, he was competent at his PR job.
Customers invest a lot in these boxes on the promise of things to come, personally i'd rather have a lot of trailers of games years ahead of release so I know what I can look forward to. That doesn't take away the need to have this year's lineup though.