I do think one of the major problems is that every fight follows a script.

So you know at certain parts of the fight the boss pattern changes. And as long as you know the pattern, nothing will require your role to really shine.

Even in situations where adds appear you know where they spawn, etc.

Bottom line they need to put RNG in the scripts to where some fights you cant predict the pattern. That would possibly open up more engaging fights rather than pattern memorization