They are obviously flying over some of the highest population corridors of New York, New Jersey, and Pennsylvania (Philadelphia). We could also ask, "Why not Iowa!?"
I think they may expand the flyovers, but these formations are relatively small, and F-16s and F-18s are not massive aircraft. Their footprint is what it is.
Perhaps they will expand their flyovers to other parts of the nation, but I think you know the answer to as why they cannot cover every mile of the United States.
I never suggested that they tour the US, but now that you mention it, that’s a lovely idea!
But, IIRC, you live in NYS? Downstate?
In addition to lifting spirits in general, I believe this flyover is meant salute healthcare workers, so they are flying over areas with high concentrations of hospitals.
And no one will see them due to high rise buildings.