I think it's over specialization. I loved that in D1 that any character could use anything. By D4 every dropped item was character specific which meant no finding cool items of a different class to build the next character around. Also just the finding items. It seemed like every item I found or listed at the shop was just another 1 to 3 points in the character I was playing primary attribute, another point or two specific to that character and a few random filler bonuses. Just boring. Maybe it got better in the later game but as far as I got in the open betas and free weekends convinced me not to buy it...

I completely forgot diablo: immortal even existed. I see it has generally poor reviews, which is not surprising.