Seeming every new version has had tweeks and changes to traders/economy, and the devs made a thread to get feedback on trader balance not long ago seems to me economy/trading is important to them. Looting has taken a hit, and is not as amazing as it once was. (its no longer required, no recipe books, nothing you can only loot and not craft, rarer high quality)
With additions of quests, and eventually factions and NPCs I feel like traders will become a huge center piece, and looting will be mainly just for those rare legendary items we have yet to see (unless they fix things and give looting more purpose again)
Manufacturing? for what purpose? the only things you need to craft in high numbers is ammo and building supplies. If you are manufacturing anything else its... here it comes.. to sell to trader.
The game is a survival game, true. With RPG, tower defense, fps, horror, a lot of elements from all kinds of genres. People who dont like trading can simply not trade. Balance of it shouldn't concern them in any way.