not sure are u troll or really stupid.  

android phone as box ?
- did u know android phone runnning normal android instead of NS running with android tv ? and most of the app streaming now support android tv, hence better user experience since u need control with ur phone. even if u do mirroring function, the quality is not good.
- did u know some of the app streaming got DRM? which u wil get limited function or not even 4k/full HD viewing. not mentioned about those HDR, vision, atmos. some of this u wont get this on ur phone.
- did u know, nvidia provide full support of the android tv even better than phone ? shield 2015 still fully supported by the nvidia to the latest android version.
- did u know, why we rather speed more money on this device rather follow ur idea ? because we want the best 4K media box can offer, best sound/visual experience the box can offer, the best user experience that we can get.

if u didnt know, then by all means, please ur phone as ur box, but dont call us stupid because it look like u make urself more stupid.   

My dad and his whole Home theatre gang after decades of using media server pc opt for media box as well. Once you have reached there you will understand. If you’re not there yet then you wouldn’t understand.