It might also be the sudden influx of outsiders, causing the "natives" to feel uncomfortable with all the new folks around. They bring new ideas, want things from where they came from, and want to tell you all about it. Growing up in the Northwest we'd have the occasional Californian move into our neighborhood, and all we would hear from them was how disappointing it was that the Northwest was not more like California. Maybe it's not us; it's you.
Doesn't really feel like a great critique of the series and more just a dislike of a less than stellar episode. It wasn't one of my favorites but I'm not sure it alienated the audience. I'm not sure that point was really made. It's also always hard to compare film, to video games, to television. The witcher has hours and hours to tell a story, the film also has lots of time to develop characters. A weekly(sometimes) TV show really doesn't have the power of that. I'd say go back and watch the Rosa episode for dealing with heavy themes well. Arachnids in the UK really felt like a throw away episode without a lot of tie ins to the series theme. I wouldn't read to much into it.