I don't mean to complain about Nova, but I don't think being platform-specific is something to be applauded (in itself). It's like making your webapp only for Chrome -- that's not a feature, per-se.
Platform specificity typically comes with native performance and, in the case of Panic, a UI that closely follows OSX conventions. For some (many?) these are meaningful value-adds.
But isn't it better to be native on multiple platforms? Like Chrome itself, or Photoshop, or Sublime Text, and many others?
You are never native on multiple platforms. You are always alien on all of them.
Unless you have separate code base for each.
Yeah it's like celebrating shooting yourself in the foot.