If you want to claim that the forest that is there now is somehow dramatically worse for insects than the forest that grew there before, that's going to need some evidence behind it.
There was a study done. I’m not sure exactly the study, but it’s from a book called Natures Ghosts. It talks about a Roman farm from around 0AD. The farm plot was clear cut, while the forest around it was never touched, including up to this day. The scientists cataloged the plant and animal species from both the farm plot and the untouched forest. Even though the farm plot had massive trees, and hasn’t been disturbed for 2000 years, the difference in species was massive. On the ancient farm plot: many parasitic species/invasive, off the plot: more prominence of delicate or unique species; just a few hundred meters apart. This is what “different forest” is.
The study describes it like this, which sounds like it's the opposite:
> Plant species richness strongly increases toward the center of the settlements, and the frequency of neutrophilous and nitrogen-demanding species is higher.
When I hear things like "delicate or unique species" I get the feeling it's not a particularly scientific conclusion.
So if you read the book: this is from a chapter talking about humans introducing phosphorus fertilizers to the soil has long term impacts on the types of species living in an area. Generally moving in the direction of more aggressive plants that can take advantage of the phosphorus. Many endemic species can’t, therefore are crowded out by faster growing species. The key phrase from your quote is: “neutrophilous and nitrogen-demanding species”. The phosphorus helps in the nitrogen fixation.
It's a pretty common thing that replanted forests turn into monocultures that don't have a lot of value for biodiversity. This then leads to all sorts of problems that healthy diverse forests don't have.
I don't know if that's the case with the Appalachian forests but this is depressingly common. That being said, there are good steps being taken, e.g. the rewilding projects by mossy earth.
Not all forests are the same. Old growth forests have a lot more diversity than something cut down in the 1800s, so that would fall under "dramatically worse for insects" imho.
Of course not for all insects, but I would guess that GP didn't mean highly succesful species like ants, which seem to thrive pretty much everywhere. I recommend visiting an old growth forest if you can find one in your area, they're a completely different beast compared to the ones you might be used to. It's really worth it!