For starters it's available from stores that people trust (Google Play, Amazon and BestBuy), has cross platform support (Windows, Mac, Linux, iOS, Android) and

For starters it's available from stores that people trust (Google Play, Amazon and BestBuy), has cross platform support (Windows, Mac, Linux, iOS, Android) and is a polished product. Also, you linked to "Android in a USB stick" products, that's not what Chromecast is.