Short answer: I could, but it'd be a lot of time and effort that I'd rather spend on adding content.

For example, consider the dense inventory and dialogue UI. I'd have to rework it completely to fit a small phone screen, and add UI for touch controls and make sure there aren't abilities that rely on complex button inputs.

Compatibility across all Android phones would also be a problem. I've got an older-model Android myself, but I can't guarantee that a shader I wrote that uses low-level functions on graphics cards will work the same way on older models, or not be bright red, or flipped upside down. I'd need a bunch of friends with Android phones to constantly test things for every release. 

For a company with dedicated people for something like this it would be business as usual, but I'm one guy and I have a day job. Maybe someday in the future.