The problem with that argument is that Sony is the one offering the service and the customer is the one using the service. The customer has the right to request changes to the terms of service and Sony has the right to refuse to provide the service if the customer asks for changes to the terms of service. So the customer is at a distinct disadvantage.

The logic makes a certain amount of sense, but the logic falls flat when the service is an actual product the customer paid for and the company decides to change the terms of service after the fact. The logic also falls flat, in my opinion, when the company agreed to provide the service for a fixed term or the service can (reasonably) regarded as essential.