This is why I'd like to see transmog or cosmetic slots. It wouldn't be that difficult for Bungie to implement an extra set of equipment slots that are cosmetic only, could even let you directly equip from a screen like the Collections tab. Add a cost, glimmer would be ideal since they'd just be visual. If they wanted to be greedy they could add a new material, à la Guild Wars 2's transmutation stones, that can be recieved from Eververse engrams. It also kind of sucks seeing 80% of people in the same armor sets.

I want to use some of my year one guns but they don't have mod slots now. What was the point of grinding for certain things (especially at the end like the solstice gear) only to make them completely irrelevant a month later. D1 had a majority of it's gear useable throughout it's history, why back track now? Add that to the large list of dumb backtracking they've done.