Except that fobs are out of stock....
But seriously, I have said this in the mobile charging threads as well. The answer is that Tesla should give new owners a credit to be used in the Tesla shop. It could be, say, $400 for 3/Y and $700 for S/X. You could then use that however you wish. You could buy a mobile charger or wall charger, fobs or floor mats, etc.
Personally, I find the fobs to be the most convenient way to get into your car. I can hand the fob to my wife or kids to go and get something out of the car. I can hand the fob to the folks at the airport to park my car. It's less convenient to do that with your phone and I have had the airport folks tell me how much they hate the card keys. Fobs have been around forever but maybe that's not a bad thing.