It still has more upsides than your average X as a service. Beyond what the OP already said, it lets you jump right into a game without having to wait for it to download, which is pretty big when games regularly take >100GB of space, even more so if you like to switch between different games often.
If you try a game and decide you don’t like it, you may as well end up using up less bandwidth than if you had downloaded, not to mention zero waiting time (unless there’s a queue, but usually there isn’t assuming that you have an actual paid subscription and it isn’t an absurd peak demand).
It is pretty much unplayable without the bank storage upgrades though. Given the amount of time they can save you, you may as well say that they are power.