I think the skill trees are not that bad, but there are many things I would improve.
- All cooldown skills should have their cooldown reduced with each skill point. Currently, some do and some do not. Take the Season 6 design for Ultimate skills as example.
- The Y-node branches should enhance the skill enough to make it feel powerful, both visually and mechanically. I agree with the general tenor of bringing in some of the defining aspects here, and perhaps giving more than two choices. See this suggestion.
- I dont understand why some classes have more skills than others (compare Necro to Sorcerer). Also, there are not enough core skills for some classes.
- I would love to see better information on skills, something like this:
https://imgur.com/BETwszy
On a more positive note, I like that a lot of talent points for the skills and passives come from equipment / other sources. This is well done in Diablo 4.