The reason is that Sony wants more data. There's no technical reason for it, as the game has already worked fine without it for months. This is just Sony clamping down on a promise they quietly made and that most people forgot about.

As for the extra hoops, if you're still wanting to play the game and don't already have a PSN account, you'll need to make a free one and link it. It shouldn't require any additional logins after the initial link, so after the initial account setup there shouldn't be any additional change to the process of logging in and playing.