I'm not getting what the UX problems are, and if you change things aren't there just going to be new problems with the changes? I think the default experience is a lot better than Reddit at least.
It might not be a bad experience for you, but it's a bad experience for what looks like the vast majority of people.
Don't take my word for it, look at the hundreds of upvotes in the post I shared.
Most of those things are kind of a matter of taste though aren't they? If you change those kinds of things you'll get other people complaining who like it as it is now. For example for me I think the default UI is excellent and the alternative ones I've tried are mostly terrible, but I know not everyone thinks the same way.
Other complaints are instance-specific but that's a good thing; instances can operate how they like because we have a choice, that's the whole benefit to Lemmy and federation.