On the one hand, they’re absolutely vital to playing Raaya’s Children in a desert biome, since it’s otherwise not really possible to get enough wood. On the other hand, that’s the only time they’re useful, it’s infuriating to make several stalls and click through each only buying 1-3 wood at a time. The unlimited ability to sell stuff isn’t even useful, since the only time you could use gold elsewhere also has a sale option.
And honestly, it’s just not even a fun or sensible mechanic to be spawning generic merchants that only have 2-6 items to sell. It would be a lot more fun if merchants’ stalls had a random merchant pass through every day or two, essentially acting as a more frequent, convenient version of the existing merchant visits. Bonus points in that you could have an array of merchants with more bulk or variety that only appeared at merchant’s stalls. Which would be especially cool since playing a trade town would actually be practical, since right now there’s not much point in paying for things you could make yourself with less effort.