Ah, good old RNG, my nemesis. My best (worst) item fail was a highly sought Deathless, with Knife Drain.
A good portion of my complaints about itemization and drops would be relieved if the drop-engine was a bit smarter in how it applied modifiers. Not everything should be godly, as you said there is a range. Damage/capacity along offers a wide variation, plus elements, anointments and other buffs. There is still plenty of reason for grinding.
I wonder what their reasoning was for having the part determine the level of the weapon instead of the other way around. Higher level weapons should have better parts. Sure, while leveling, I often used items far below my level because they just performed better than what I was getting.
But if a higher level version of that item dropped, I would expect it to have better stats. Do you have any level 49 weapons that you use over their level 50 versions because of the benefit of a level 49 part? I honestly haven’t looked closely at anything that is below level 50, unless it’s a rare legendary or something new to me.