Random elements in itemization bring extra build variety, this is the main net positive.
Putting aside that as a single benefit it would be pretty slim, I don't even particularly agree with this point.
One of the cornerstone of "build planning" in videogames is predictability. You need to be able to predict where and when you get what to plan for a build.
Randomized loot ACTIVELY works against it, forcing you to deal with the hand you are served.
Now, there may be arguments about liking this in principle (card games are based entirely on this principle, for instance), but that's another story. And on a personal level I would also disagree on considering it a plus.
Aside of not liking it flavor-wise, my other argument about disliking randomized loot (and tangentially also an excessive amount of randomized/respawning encounters) is that the feel I get out of these is FAR from "Oh, look at all these diverse and unpredictable experiences I'm having" but rather "Why does every part of this feels so samey and a worthless waste of time?".