why no one combines android and linux?

Android is ruing on the linux keel. I know that it doesn`t use the X-server nor a libc or popular linux’ GNUs. But if the core is the same, why can no one make a system that combines the both? Why no one puts the greatness of Android and its touch screen capabilities, on a normal Linux distro, or the other way around- why no one puts Linux’ great features on the Android device (as a ROM or something)?