I've been working with Haxe and OpenFL for about a year and a half. A year ago I would've agreed with you, but the past year has seen some major advancement in all of these areas. The Flash API is more fleshed out at this point. Setup still has some quirks but I find that once that's taken care of, compiling for multiple platforms "just works" and is incredibly convenient. For example, OpenFL will actually download and install the Android SDK and NDK for you, then compile your application and sign the APK with a single command. The most popular game engines (HaxePunk or HaxeFlixel) are great at smoothing over some of the platform-specific differences in things like rendering. It's not a magic bullet and you still need to have a basic understanding of each platform you want to target, but Haxe and OpenFL make things so much easier.
