But in practice, that speech is the most important bit - and the most neglected. People watching a presentation tend to stare at the screen. Even people giving the presentation stare at the screen. Instantly, all feeling of interaction, of communication, is lost. The meeting is reduced to a communal TV-watching session.
Presenters tend to take cues from the slides they are staring at.
They end up being ruled by the slides, not using them as a tool to illustrate their words. Worst of all is when copies of presentation files, or print-outs of slides, are given out to presentees, as though giving them this copy will help them understand. Nonsense, it provides them with something to doodle on, and ends up being another distraction from the important task at hand - communication. So I have my own preference for presentations. Most important is a speaker who is confident and knows their stuff.