So 2 things:
1. Premium connectivity isn’t unlimited bandwidth. At Halloween last year, I used the scary machine voice thingy in live camera sentry mode to spook kids on the street. I played around with it for a while, then I got an error message along the lines of “you have used all of your bandwidth for today”.
2. OTA software updates are around 0.5 to 2Gb, depending on the update. That’s a lot of bandwidth (google says Netflix uses around 3gb per hour for HD streaming, as a comparison) and I suspect it would just take a long time. (~40+mins for a 2gb update). While it’s not a showstopper, it costs Tesla $$, even though you offset some of that cost with premium connectivity. Which brings us back to point #1.