Pandering is the wrong word. People have been using that wrong.
People are just kind of sick of Kanto leaving others in the dust and they aren't able to vent their frustrations properly.
I guess it's just something I won't ever agree with I suppose.
Like I never felt as someone who likes Gen 1 that I was being "pandered" to with Gen 6, if anything I felt they were trying to make old Pokemon more appealing for the newer gen fans by modernizing them with Mega's. The same concept also applies with Alolan forms as you can tell by their designs they are more "modern" in concept.
Not only that, but I feel there's a logical explanation to why each thing happened.
Gen 6 introduced a new evolution concept and each gen (except Gen 5 which only got 1) got tons of new evos and it's better to use older Pokemon in this situation because of the way they release games slowly but surely and trickle out mons over the years.
Gen 7 was during the 20th anniversary of Pokemon and Kanto is the most recognized region and the Pokemon from it are the most popular of the whole series, so it makes sense to appeal to the fans by celebrating the legacy in some form or fashion. It also allowed them to not have to create a whole slew of new Pokemon because at this point, let's be real, they are starting to run out of ideas on monsters cause they've done almost everything they could do. I think if they adopted this "alolan" concept with later gen mons and trickle it out each new generation it will be good from a game dev standpoint.
Let's Go is designed to appeal to the mass market using the most popular Pokemon and region, but they aren't neglecting the newer fans as they are putting in the effort to releasing a brand new generation next year. Like regardless if Let's Go existed or not, the game still would've been 2019 because Gamefreak needs time to make a proper next-gen (for them) Pokemon release.