You guys used to do it early on and in D1, I assume the main reason it was removed is that balancing was harder with the changes each sight made to zoom, aim-assist, etc. but is there any chance it could return as just a cosmetic change, no stats related to it at all. Not all the sights in the game are great and certain weapons are better with different sights, 'Duty Bound' is a good example, if you inspect/buy the original version in the collections(can still change the sights) it has a nice red-dot sight with thin sides, the other option before it was sunset (which is also its current sight) is a thick brick that's honestly hard to use or even look at, I know quite a few people that don't use it specifically because they hate the way it looks. I'm also sure some people have their preferences in general, like some want scopes on everything, and some may want red dots, holos, or even iron sights (which hardly exist in D2, that's my preference), overall it'd be nice to have the option, even if it's the same like 6 sights recycled between every weapon, or even a few for each weapon foundry. EDIT: Along with @Exalted IV's suggestion of placing it in the cosmetic section where Shaders & Ornaments are, (assuming it might be even easier this way) it could also work similarly to Revision Zero where each upgrade was a slight change to the weapon and a new ornament, the sights could be classified as ornaments. Like @Darth Drav3n said, have Banshee sell sights. This also inspired me to expand on the idea, since they'd probably permanent unlocks make another slot like the weapon mod slot, the 'sight slot'. If there's a limit to perk columns like some people are saying, and assuming there is also a limit on the row that weapon mods are in, place the sight slot where deepsight stuff would be, unfortunately, that would mean we would likely only be able to swap sights on non-craftable weapons, but something is better than nothing.