We want adults to play the game :) having free versions means lots can try it out, and having paid versions help support us to make more. Many people who just have an android might not be an adult. And all versions will cost the same once we get the next update out. Hope that helps!
Thats honestly smart i do see a lot of Tablet kids wondering around the internet finding these games, and wanting to try them, so i can see that paying for a mobile version would make things safe, but will it ensure that when the user purchases the phone version, they will then get access to the full release?