For one it felt too easy. Some of this was likely console controller vs. mouse - and so maybe not the game itself’s fault - but it felt like point-and-click turned into just click, making it more one dimensional.
And two, I felt less weight/permanence in character building decisions. One of my favorite aspects of d2 is specialized builds, that you can screw them up, and generally delaying spending skill/stat points until certain. I thought d3 character customization felt more cosmetic and like my choices ultimately didn’t matter as all builds were so strong. Like it didn’t matter how I allocated points on my tree in the same way it felt like navigation and attack, described above, had lost some nuance. And that seems off to me when every character pretty much plays as a gear-independent caster.