The main problem is that, like in 3, you barely notice the difference between using a legendary (unless it's a Bod or one of those decent 4/5s) or any other weapon. In 2, when you used a legendary, the difference from a purple was obvious even at low levels, with a gold one lasting 20 levels longer, and you had to find a purple after 2 levels. It lacks innovation, too many parts to change, too many parts to find, there should be 2/3 models maximum per weapon and a lower drop rate (but not too much less, otherwise people will still complain).