RNG - One step forward....
I agree it is all very frustrating. Allowing them to be traded was a good move and I know they need to make profits, but having the scraps be chance based as well is just ridiculous. The whole point of a scrap system is create a sense of, “well I didn’t get lucky, but at least I know I’ll get one eventually”. By adding chance to the scraps you completely undermine the philosophy.
What is even stranger is the weapon drops. It is good we can get the skins through game-play and I think it was an incredibly clever idea to have them as actual weapons. This way, it requires people to purchase transmute stones in order to use them. The customer has the satisfaction knowing they have the weapon and Anet can guarantee at least some investment in gems with some of them no doubt being through cash. Why they didn’t opt for this to be the main concept rather than using the Black Lion chests I don’t know.
Use chests like the Dragon’s Bash Coffers for the world having a chance of weapons that require transmutes, Black Lion Chest boxes having guaranteed scraps and the low chance of a golden ticket for a skin of your choice. All three ways have the same requirement of some gem store interaction while also giving people a greater sense of optimism.