Aside from any business/ philosophical reasons they might have, one concrete reason for this is that the App Store prohibits apps from asking for accessibility permissions, needed for recording keystrokes, which I imagine would basically make this app impossible!
I have Moom installed from the App Store, it requires the Accessibility feature to be flipped on in Privacy and Security -> Accessibility before it'll work.
Interesting, maybe they've changed this since I last looked at it. At some point I was pretty sure that Accessibility required unsandboxing, but App Store required sandbox enabled.
