Well, I see people tripping over themselves to find reasons to dislike it but I think this is relatively fun just taking it in stride. MC isn't a genius or anything sure, he just finds out what people are lacking and sells it. I don't think he'll have that much trouble staying in business on the fantasy side as long as people just accept that he has magical assistance in procuring his goods. I suppose if the Japanese version of the IRS is as tenacious as the US there could be some valid concerns there but are we really going to take points off for realism like that? Certainly I'd support the suggestions to come up with something to sell back in Japan to use as a cover, though I'm not gonna hold my breath on that development.
I dunno. Is it amazing for being isekai trash? Maybe not but I don't think there's any reason to come down too hard on it. It's not like it's offensively bad or inconsistent (so far). Anyone who feels THAT strongly about this one might just need to stay away from all isekai for a while and cleanse the palate. I won't be the one to let a little thing like inflation (or would the issue be deflation here?) get in the way of my fantasy.
For the folks worried about the harem stuff being intrusive, I don't see signs of it. What I can see is one potential romantic interest (with the usual everyone's too shy to have it progress anywhere. I'll be happy to be proven wrong though). Seems like they just preferred having the more prominent side characters all be women since that's what sells. Though I will admit that I never find the 'MC spotted in an easily misunderstood situation" joke to be funny. But that's Japanese humor I guess.