This is a technically interesting topic, but I hope it's not the main thrust of Netflix's attempts to provide better anime.
I know this is subjective, but my enjoyment level for a given anime is unrelated to it being in 720p vs. 4k. Death Note would have been just as amazing in the 1990's, because it's all about the story. One Punch Man is just as funny at 480p.
The only existing anime I can think of that might benefit is those with high-end 3D CG battles. For example, if someone did a really decent remake of Robotech, maybe 4k would add some visual realism to the space fights.
A lot of good anime are good because they don't put a lot of effort into cutting-edge graphics but on other elements (characters, story, animation, etc) => using 4k and/or HDR might just drive up the costs without providing a real benefit.
And on top of that, some of the technological "advancements" actually make things worse. Personally I loathe the trend towards 3D-rendered "anime", artificially stuttered to make it resemble a hand-drawn animation. The only time such techniques are appropriate is when showing something mechanized. Used on regular characters, it looks terrible. Knights of Sidonia was a great show, but it looked really bad. The visually-best recent animes are ones like Devilman Crybaby that really embrace the hand-drawn medium and run with it.
4K makes cheaply animated content look cheap. Sometimes that's ok, other times viewers want more.
Another example outside anime is Fantasia 2000 on Disney+. That kind of content requires high fidelity. Disney+ looks and sounds bad and it harms the content.
I think it's fantastic Netflix is doing what they can to make fidelity a competitive advantage for content creators, especially the ones that can't spend as much on it.
I know this is subjective, but my enjoyment level for a given anime is unrelated to it being in 720p vs. 4k. Death Note would have been just as amazing in the 1990's, because it's all about the story. One Punch Man is just as funny at 480p.
The only existing anime I can think of that might benefit is those with high-end 3D CG battles. For example, if someone did a really decent remake of Robotech, maybe 4k would add some visual realism to the space fights.