[DCKing]

Text heavy slide creation tools (such as LaTeX and Markdown based ones) are aimed to make slide creation easier, not actually watching the resulting presentation. It's not to say that you cannot make nice slides with those tools, but using systems that make it much easier to write text than to visualize really promotes the wrong thing for presentations.

People don't tend to notice this as much though, and they are more concerned with familiarity or speed-of-production of the slides rather than make the slides effective for the audience. But hey, that same issue can be raised for most PowerPoint presentations, too. People just don't know how to make good slides and just take whatever is easiest for them.