Except it's not really an upgrade. It's preventing usage of capacity YOU ALREADY OWN.  And I kinda doubt most Tesla owners know that they really owned 75 kWh battery but were being disallowed from using the last 15 kWh of it.  

They can get away with something like this (PR-wise) if few people know about it.  But it's a different matter when more people find out.  It's like giving you a back seat and 4 doors, but then locking the doors remotely so you can't open them unless you pay them 5 grand or something.  On your OWN CAR.