On desktops/laptops, keyboard shortcuts save reaching for a mouse, aiming (on the relativley large screen), and clicking. On handhelds, I don't think it's faster to use a shortcut than to simply tap something an inch away.
Also, on handhelds, the keyboard blocks a significant part of the screen. And keyboard shortcuts typically use accelerator keys, which are hard to use on handhelds.
Do you use Android with a physical keyboard?