It feels to me like some of the numbers need changing, for how rare/not rare things are.
In particular, it's not JUST crafting materials that appear in stashes now, there's also lots of the new things that players will be wanting later, the profession books, the "gift items", and stuff of that nature. AND, there's also the stuff that was ALWAYS there.... Shards, platforms, crates, Glyph Transfer Scrolls, Elusion Scrolls, and the various different area-specific things like Moon Lamps or the Dino transmogrify scrolls. And I still think Platforms and Crates are way, way, WAY too common. I have 10 squillion platforms.... I dont really need to find more currently. Heck, I often wonder WHY the Opal store has those 2 things at all, considering how absurdly common they are.
Anyway, the more possible stuff there is, the more rare any given thing becomes, by the current system.
At the same time though, I wouldnt want them to be common enough that I'd ever really have a major surplus of the things, as that breaks down their importance. And I know the current version of the game has an entire set of mechanics that ARENT fully in place yet (the citybuilding bits, and stuff like being able to send other survivors on missions to get stuff, or whatever it is you send them to do). So that might be affecting it as well, the current balance may be more geared towards the point when that's all put in place.