Let’s be honest, not every movie “needs” to be in 4k, but some really gain from that additional resolution - and that’s ignoring seating position and screen size. What are your favourite movies that you’d recommend in 4K over the same movie in 1080p?
For example, I always prefer Christopher Nolan movies, anything shot in 70mm/IMAX film and anything animated, set in space/fantasy worlds or BBC Nature documentaries to be 4K (and HDR preferably).
Willy Wonka & the Chocolate Factory.
More accurate colors, and they fixed the longstanding issue with the bluray 1080p release where the frame wasn’t cropped correctly, which made it so you couldn’t see certain things you were supposed to see, and saw other things you weren’t, like empty parts of sets or camera shadows, things like that.
You can see what I mean here in this review with comparison shots: https://highdefdiscnews.com/2021/06/24/willy-wonka-and-the-chocolate-factory-4k-uhd-blu-ray-review/