I don't like that either, but I think it's a nod to the fact you're buying into the Tesla Supercharger network up front.
No other car companies sell cars with pre-paid fuel option (for the life of the vehicle).
They just need to show / reflect the value received for that investment you're putting in at purchase time.
And if Tesla is going to do this, they should match the period to their warranty of the powertrain, so show a "gas saving of 8 years".
It's all just fun with numbers anyway. Everybody (should) know to configure a vehicle on "cash price" and constantly look at the bottom line, as options are played with, and only after everything is added up... that's what you pay and is the only thing that matters. Then determine your financing arrangements to pay for it, lease, whatever.
Tesla wants to terminate the idea of "opting out" of SC network.. they need to pay for it. That was a weakness of the model 60 offering, as it allowed deletion / addition of SC network during order time and after the fact. It put a price on it: $2500 (IIRC). What does gas cost for 8 years for a sedan of this class? More than that.