Interesting comment. But then again saying "terrible" is easy. On the other hand, how do YOU present ideas, concepts and information to your clients and audience? I am open to suggestions.
When presenting a method or a program to students, I try to start from as scratch as reasonable. I recently prepared an experiment for a student of ours, and essentially wrote the program in front of him, running it at intermediate stages so he could see it evolve. He felt comfortable changing the functionality afterwards, so I expect the information transfer worked. I've done the same before with small student groups, creating something minimal, but perfectly understood.
For negotiation situations, I prefer doing them in person or at the very least over the phone, but preferably so that I have all the data in front of me. At that point, I want the other person's attention focused on me, not on the projection screen.
When showing a thing, like a program or a concept, I like to show the thing rather than showing something that shows the thing. I'd explain it and demonstrate it rather than showing slides about it. I might show photos of it being used in situations I can't directly reproduce.
In all of these situations, slideware would not have noticeably improved things. And it's always a timesink, for me at least.