Rooting Kindle Fire bricks videos

The Register has the story that rooting your Kindle Fire will break the ability to watch videos on it. This is not a technical failure but a acknowledged policy of Amazon. The solution to it is already available too by changing the name of the su command. It is known that Amazon sells those devices at a loss in an attempt to gain marketshare. A tactic widely successfully used in selling printers. Of course they want you to buy their stuff. Rooting makes installing alternate content and apps possible so they do not like it. But why did they choose android to run this devices in the first place?