Because of the chance at getting an awesome roll. It made every drop feel unique. I loved getting the auto rifles with the perk that made them shoot slower but with more impact when you were ads. IB guns also had random rolls. I don't know if you mean the vendor's roll for IB were perfect, but a perfect roll is subjective and the best roll for one situation might not be the best roll for another situation. Even if you dismantled most weapons you get, the chance of getting an awesome roll made it exciting. The guns were at least worth looking at and seeing if you should keep them. In D2, I just dismantle everything that won't put my light up.

yeah, every drop is uniquely bad. Auto rifle that shoot slower...like SUROS...which was nerfed so shooting slower is actually less DPS than regular auto? lol. IB vendors rolls were godly, the random drops usually drop worse rolls. The best rolls were always all for crucible. Caring about rolls for PVE is meh bc Ghorn took care of everything and after it was gone...it was all black spindle ;) rolls on primary guns were pointless until pulse buff in which case that's when everyone farmed omnighoul -.- In D1, I dismantled everything....In D2, I dismantled everything.... Nothing has changed lol.