It'd be pretty nice if we could expand on the Sprite Alchemy Machines, to also enable us to craft food using Moonstone/Valestone minerals. They could essentially just act as "neutral" food, which of course wouldn't be the favourite of any pet, but could still just give a nice little boost nonetheless, slightly more so than materials.
I think a small change like that could easily encourage people to start picking up these minerals again, and of course, use them for a bit more than just a prestige mission. Would be great if we could feed our hungry sprites with them too!
If I remember correctly, this was suggested years ago, as the only other remaining use for those types of materials is the "Geological Survey" prestige missions. It's a great idea, but I don't know if they'll ever consider implementing it. :o