One of those late nights wrestling with PowerPoint for a presentation tomorrow, so I'm less than fully coherent. (Or let's say, normally coherent.) Now, I'm not the first one to point out that it's not very useful for thinking, or that's it's just not made for Macs, or for actually convincing people of anything if they're not engineers, but all of those things are so manifestly true to me at the moment that I must bore you by reminding you of the fact.
I know people who default to Excel when creating any document; they think in those key commands, even for lists and other "natural" word processing needs. And as I writer, I've come to a South Korea/North Korea kind of understanding with Word. (I really miss MacWrite II, which was 20 times smaller, faster and 99% of the time just as useful.)
I don't know anyone who thinks in PowerPoint. I'm not sure I'd want to.
It makes everything dull and uninspired. It takes really good ideas and turns them into bullet points with different kinds of bullets and indents. It turns people into robots at the very moment when they need to be inspired and passionate and creative. It's a straightjacket. A vise. A trap.