Hard to learn against something that can be ever changing and new, especially considering how many others got hacked in such a short amount of time after Sony.
The learning has to do with not changing the game on their well paying customers, not with sealing their breaches. Sony changed the EULA to the "you can't sue us". And there has been no attempts to bring back the linux console. They also continue to force you to update the firmware or else not be able to play their newest games.
It's pretty much business as usual for Sony, they are acting just like before the first attacks.
That's what was meant by Sony has not learned it's lessons.