There's no reason not to use almost entirely gestures now, as @mscion hinted at, if you're happy to root your phone (usually a simple process). The gesture options are also far more comprehensive and configurable in Android than we've ever had access to in 3 years of 'development' of Sailfish, as a supposedly gesture based OS.
Simple. The OSS market is not worth the effort. Haven't we learnt that by now?