lets take Droid DNA for example
This phone has a 1080p screen, torrenting a 1080p full Hd movie will take at least 4GB with some blueray rip around 7GB. In Droid DNA, you have 16GB with usable storage of around 11GB, minus all the other stuff on the phone such as photo, books etc you can only fit one full HD movie to take advantage of the 1080p screen.
Are you serious?
If Google feel that apps installed on SD card will affect the performance, that make sure all apps are installed on internal memory, since they are all quite large in size now days, but expandable memory for movies and videos, which are non operation vital but takes up large storage.