I started thinking about this as I sat in the audience of the @devs #Fastly live event on Thursday https://www.youtube.com/watch?v=pgNjS1_kOW8 during which they announced some no-kidding good things, such as a significant new service donation to some open source projects.
And: a curtain was rigged up to add polish to entrances and exits. And speakers asked us to shout "instant" at them.
A proper product launch, these days, is accompanied by a dramatic ritual, and Jobs and Engelbart were not the only forebearers.