All legendary items should be created with max slots. This means 4 for ranged weapons and torso clothing, and 3 for melee weapons and other clothing. It is fine for stacks to vary with common-epic items, as those are basically replaceable. However, if a player finds a legendary with limited slots, it can be really bad. I am now metagaming so that if I see a legendary red-orange loot square, I always save my game immediately then reload until I finally get it to spawn with max slots before picking it up. Why? Because I want to *use* the legendary, and a slot is frequently more powerful than anything else, especially on armor.