Lets be honest
Making a presentation is a performance
Most people are NOT performers
Good presentations require good design skills and a great script
Its like writing, directing and acting in your own play or film.
Mike the great guy in sales who always fixes the hard to get football tickets, or Tanya the Professor of Bio Mechanics don't have these skills. Frankly if people do, they are just as likely to be up there winning Oscars.
Too many presentations are put together by wonks with a background with large consultancy firms. They are trite and repetitive (books don't have a chapter of contents at the beginning of each new chapter, why keep repeating the contents slide all through the presenbtation). Most of these people have a Tech/B School background, their design skills have never been challenged and most of them did the bare minimum in literature papers as it appeared to be non relevant.
In the real world, amongst the most valuable skills is that of being a good communicator, giving somebody who is not a natural communicator a tool, be it Powerpoint or something similar, does not fix the comminication problem, it agrevates it.