If there were build tools that could help deploying to the App Store/Google Play/Windows Store/Amazon Marketplace in a straightforward way, this would motivate

If there were build tools that could help deploying to the App Store/Google Play/Windows Store/Amazon Marketplace in a straightforward way, this would motivate people to write more portable software. Those marketplaces are not only places to buy applications. Many applications there are free. They are also distribution channels that help people finding and installing your app.