You knew Simpsons World wouldn't last much longer when Disney+ claimed The Simpsons as a streaming exclusive, but you might not have expected the end to be so... abrupt. Simpsons World has promptly shut down, making Disney+ the only place to watch every episode even though it's barely available to the public. While that makes the show accessible to people without cable subscriptions (and outside of the US), it also pushes cable TV subscribers to pay extra if they want to witness Lisa's perpetual motion machine or Homer's near-death experience.
This wouldn't be so much of a problem if it weren't for the current state of The Simpsons on Disney's service. Right now, you're limited to cropped widescreen versions of older episodes. If you want to watch them in their full 4:3 glory, you'll have to wait until early 2020 -- you can't go back to Simpsons World to view them as intended. Although this isn't necessarily going to break your heart (especially if you still have Simpsons discs), it does illustrate the dangers of quick transitions and streaming exclusives.