Pls only read if you are suffering from insomnia.
I find it informative to look at the artist's original intent and then the effectiveness of their execution. You may never get a direct answer to the former (see: Mona Lisa) and the latter is subject to a thousand opinions, all of which are valid.
The Desert Trader originally gave free coffee (every 10 minutes before that exploit was fixed) at the Night Market and was a brown-skinned woman in a turban. Perhaps she didn't need the turban but then perhaps her character design could have been anything else, including a Shadow Spirit, Talking Bear, or a Pig in a fez & shades. The chosen characterization seems reasonable and as a single-use NPC, she did not stand out any more than the Mustachioed Victorian Gentleman who hosts the Deep Sea Fishing venture. He is at least as much of a one-use stereotyped character as she is, or the Governor. They serve a purpose, though perhaps some less-traditional gender roles could have been considered for the NPCs.
I liked the addition of the Desert Trader's post to the Calico Desert as she seemed to fit in there pretty well, and she allowed for an expanded use of materials for access to Skull Cavern. IMO, the inclusion of Bombs to her suite of options is consistent with being useful in the Skull Cavern in exactly the same way that Bombs being sold by the Dwarf at the entrance to The Mines are useful in that place. That Bombs were already sold by the Dwarf before the Desert Trader's post was added to the game shows what CA's intent was: to give you easier access to tools which add to the strategy of the game.
CA could have added a new NPC to sell to you in the Desert and then that person or magical being could have been anything. Instead he chose to expand the visibility of an existing one-note NPC, for whom having a trading post in the Desert would not be a big character stretch. Additionally it seems that the Desert Trader is also a nice match with the Wandering Trader, both of whom are women. Taking those 2 things together does make it seem to me that the Coffee Merchant morphing into the Desert Trader was a good choice in game.
That she is brown-skinned and sells Bombs is an unfortunate correlation that some will choose to associate with some sort of social commentary. I don't feel that was CA's intent and as many others here have pointed out, she is neither the original nor exclusive source of Bombs, and Bombs are an in-game tool for a particular reason: to clear spaces. There are a great many other stereotypical elements to this game that were intentional (Haley??) which IMO could be discussed with equal validity, including Anhaga's note of the sparse diversity in the Valley.
I suppose in the end I am of 2 minds about this, which is difficult as I can barely string along one coherent thought. One is that it's just a game, made by a guy who squeezed blood from a stone to make it happen and unintentional transgressions are to be given the benefit of the doubt. The Principle of Charity: Always assume that the person you are engaging with has the best of intentions, not the worst. But then you should still have a dialog like this one about how to make things better and more equitable. Because all these stereotypes, big or little, serve to entrench old ideas and keep them as the norm. How are we to understand someone else's viewpoint on anything if we don't at least acknowledge that there's a problem in the first place? That needs to happen first before you can try to fix it.
Yeah OK, I'm done.