I thinks is a must.
Problem: There is too much OP builds who one-shots everything. Especially when you play as a weaker build, you barely touch anything, which is boring. I don’t think one-shotting everything should be viable in this game. This is not normal ARPG combat, it should reward skill, not numbers.
Solution: More difficulty to choose, at least two, more the merrier, and not just buff enemies, but give them faster reaction times, more skills etc.
Solution 2: Once you finish the campaign you can start again with higher difficulty, and then again, and again… indefinitely.