This is great feedback and something I can do better. I had actually done a retrospective on the change of the landing page but you're right... it still needs improvement.
At some point I'll probably hire a "real" designer to help me... since i'm not a designer by any stretch of the imagination.
I wouldn't even say it's a design issue. More of an information issue.
If there's no demo available, I need (as a potential purchaser) quite a bit of information to know if it's worth risking my $$'s. I'd say some combination of screenshots/gifs or screencasts going through the program would be great. Or maybe more of a focus on the workflow, or maybe just expanding your features section to be illustrated with screenshots form the app showing how features are used.
Honestly, some of the best descriptions of the program are in App store reviews where it's compared to other distraction-free/markup writing environments.
At some point I'll probably hire a "real" designer to help me... since i'm not a designer by any stretch of the imagination.