Apple also has a large and growing editorial staff writing articles and highlights for their App Store; it's virtually becoming a house magazine. So being in th

Apple also has a large and growing editorial staff writing articles and highlights for their App Store; it's virtually becoming a house magazine. So being in their store potentially offers exposure and marketing for free that's immensely valuable. (Whether it's 30% valuable is debatable, of course. Personally I think they should drop it from 15%/30% to 10%/20%, but "Apple: always more expensive than you think they should be" has worked for them for a long time.)