Mostly because Substance Designer is yet another app in a app overflowed workflow. You have to deal with file conversion etc. With dDo and nDo you just stay in the app that _every_ artist out there already know and hopefully are familiar with.
Kinda... http://www.collectingsmiles.com/colors/ (the app) http://colors.brombra.net/?page=1 (the gallery) It rocks my face off. It's actually pressure sensitive!
For quick n' dirty OSX apps I'd go with RubyMotion. I think the right niche app could sell well, see Pixelmator as an example. Just like iOS you'll probably want to integrate with as many of OSX's latest new features to get featured by Apple on the App Store. For games the Mac App Store probably isn't worth the trouble for…
When creating Hero Academy we had faced the same questions. We had time to design the game around what we felt most comfortable doing. * No pay to win. * Fair amount of content for each In App Purchase. * Nothing is gimped if you don't pay. * Use Ads for free players. * Remove Ads for any In App Purchase made. * No Ads…