Here is an idea to go on top of your idea. We have engrams and blue prints and stuff. What about adding a crafting vendor? Here is how it would work. There are multiple designs and foundation pieces you could choose from. Now each piece of gear can only be leveled up with motes of light and engrams. So you would take maybe 10-15 blue engrams of the same kind of piece, if it's a glove blue print you would need glove engrams. The motes would be based off what "tier" your piece is at. Also each piece would have multiple paths you could take and it would depend on what planet material you would use to level it up as well. Also after each tier you would have to complete something difficult to get a drop to add to the piece to get to the next tier. This is just a broad idea. Although I think that some sort of crafting system with gear would be an amazing add to Destiny.