At the time this firmware was made, they probably hadn't even built the convection roast mode.
It needs WiFi to update the firmware to one which hopefully does perform as promised. After that you can probably disconnect the WiFi again.
The game industry does this, which is crap, but appliances are people use to cook their meals and should not be unfinished.
If you are right, it should be illegal.
That's why they develop the firmware while the hardware is on the boat.
With games and games consoles it's really noticeable - there is no games console you can buy and use without a day-1 update to make it functional.
No, it's fantastic. If they did what you think you want you'd get the same games perhaps a year later.
So because they're doing it you can get what you'd have gotten anyway and more, because if you just buy games after they've been out for a while you'll likely get a large discount.
And people who are big fans of the franchise can get the game earlier if they want, and essentially pay for being beta testers.
It's a win-win.