I think the LOTR 4k version is still okay. I watched it, the audio is great, HDR is great, some of the color grading is better (no green tint in FOTR), and some of the shots do actually look more detailed especially shots where you can see miniatures in the background, you can notice things you never noticed on 1080p. However, I agree that the DNR (less film grain) completely sucks. I love film grain, and the waxy look in many of the shots is unfortunate. I think a color corrected LOTR Blu-ray fan edit would probably be the best way to watch LOTR for me.
As for Hobbit, it never had film grain so it’s not going to have much or any DNR I bet, but I never watched it so maybe you are right it does have problems.
For me, the reasons I don’t want to use the 4k Hobbit as a source are because: have to redo the color grading, I need to upgrade software/hardware/purchase the discs & a new disc drive, and even when I finish most people will still not even want the 4k version because it’s too big of a file. I have done some additional color tweaking in BOTFA in my edit’s next update to help reduce the excessive glowing highlights, so whatever improvements the 4k version made to the look of the films I think my edit at least isn’t left in the dust because I have tried to improve the look as much as possible.