They already pick up gold, but what if they can do more.
#1- Different pet different job - Some pet pickup gold some other, yellow mats(or all mats), some other pick up blue gear. ( with or without gold). ect ect.
#2- Open the Pet menu and select what you whant him to pickup. check box for - gold, mats, gem, white gear, ect ect 1 at a time or most (pet level maby)
#3- My favorite. Pet have Level. after 10k of picking up thing he gain a level. He now able to pick white mats. lv3 blue mats. lv5 pickup yellow gear, lv10 pickup legendaries.
Open the pet menu and check box what you want him to pick up depent of his level. But pet can pick up everthing in the game at his max level. or make a choice betwen4/10 pickup option if you think that a max pet level making him able to pickup everhyting is too OP.
As useful as this option might be, it goes against Blizzard's views of how the game should feel. As it is, drop rates are already too high and hiding those drops (players don't need to pay attention to them) only reduces the rewarding feeling associated with legendaries. I personally dislike having to stop so frequently to pick up death's breaths, crafting mats and gems, so I would welcome an option that picks those up for me. On the other hand, the idea of a completely passive looting system is unappealing to me. I would prefer the option to auto-scrap white/blue/yellow, coupled with a better inventory management system. Either way, I doubt we will see this sort of functionality in the near future, if at all.
Yeah as OP sayed, would be cool if pet could pick up pure crafting mats and DB's. Could also make it a feat of strength achive to unlock this to make some "mandatory" grind and "content" kind of... I know many of you out there would not like my suggestion but isnt a ARPG about some grinding all in all ? Peace =)