Traders giving you game-breaking equipment could wreck your progression - game over, end-game equipment before your second hord night. I remember frequently them giving you level 6 something or other, a not-to-be-missed opportunity, and I'd miss out on something that was less flashy but more integral and much harder to find, like a beaker. The missions themselves are the best part, with the chance to find better loot with a tougher challenge.
The current rewards are kind of measly, but the lifetime of the survival aspect is expanded and you do more crafting than you've done before. For what it's worth, I still find the stuff they actually sell a little unbalanced. Very next trader I went to on the opening supply route mission had a level 4 iron crossbow in their inventory at a price I could afford. At the time I could only make a level 1 wood bow. I'm also working my way up the iron tools and suddenly they're offering me steel tools.