I will preface this by saying I don’t think this would be good for developers but I do think this would be smart for Apple to do. It would be a good bargain for customers until they learn the caveats of the Mac App Store.
Would you buy the Mac App Store version of an app if the iPhone version came free with it? What about getting a discount for the Mac version if you already owned the iOS version? It would be a no brainer for a lot of people. If there was a choice between a discounted price in the Mac App Store and buying it for full price on the developers website, they would buy it in the Mac App Store. Apple makes its 30% from the sale and they are happy. The customer is happy they got a deal.
There are significant problems for both developers and customers that come from buying and selling in the Mac App Store. They stem solely from the rules Apple makes developers follow if they want to be in the MAS. I wrote about this before, and while I don’t want to get into it again here these rules are neither developer nor customer friendly. Buying an app in the Mac App Store can mean getting a nerfed version and no upgrade pricing. For developers it can mean an unsustainable cash flow. Apples rules are really limiting what apps in the Mac App Store can do and it’s causing developers to abandon it altogether.
I really think Apple has to address these issues with the Mac App Store if they want to sustain those contributing to their ecosystem. The fact that good developers can’t make a living in the Mac App Store should scare Apple. I have a feeling that it is of little concern to Apple because another developer will always take their place. Developers are the lifeblood of any digital ecosystem, Apple should enable them to thrive not drive them out of business.
Cross platform bundling might make Apple a bit more money but I think the greater motive would be the experience. You buy something on your iOS device and when looking to buy a computer you choose Mac because you will get discounts on all of the apps you use. It could also drive more people to purchase through the Mac App Store which is a great experience, until you learn the caveats.