And how much does it cost to build and maintain your own domain, storage, delivery/updates infrastructure and billing system? Oh, and how about marketing for your app?
Sure getting featured helps, just like if a fashion designer has a celebrity photographed in their clothes, they will probably see a temporary bump in sales.
Getting featured on the App Store is one time, possibly incredibly beneficial, event, but it is not a marketing plan.
Ask developers how much difference being made a featured app makes to sales. Apple recently radically redesigned the App Store so that it could more effectively promote apps.