What are some of the reasons why Nintendo Switch isn't just phone + app + chromecast-like device + bluetooth controllers?
$300 for a tablet, chromecast device + bluetooth controllers that all integrate nicely is a pretty good deal. Gaming on mobile phones with controllers is a pretty janky affair right now. Poor quality controllers and iffy compatibility are the norm. Getting your display remoted to the TV is also well in the "doesn't always work" territory.
That people are using controllers with phone games tells me that there are still lessons to be learned from the Wii.