I’m not sure what the point is you are making with this post, other than, make money from you apps.
Having worked quite extensively with Shopify and app development I’m rather sceptical of the entire experience. The fact that apps are all hosted off-site makes your website more fragile with every app installed, adding another hosted dependency.
Majority of front-end work is handled through jquery at the client side when it should really be done server side, or its managed through proxy pages which again add another off-site dependency and need to be customised and styled separately (where even possible) making it impossible to include such changes in your theme’s source control.
Finally, the inability to extend the shopify admin area means each app has a different interface and typically doesn’t make for a very pleasant user experience and having to jump between screens all the time for things which should be grouped in the same editing screen.
Sorry to provide negative feedback, but I think there are some major flaws with the Shopify app system! I would be very interested to know some of the reasoning on how or why decisions were made for this setup.