If people are angry with the 2021 update (only due to software), why aren’t they more angry with the 2018 -> 2020 changes? Apple literally just added a graphics core, a camera and LIDAR scanner and named it a new generation.
I think it is mainly because of the huge upgrade in hardware performance with the 2021 change. Adding the M1 chip and all the extra RAM really got people excited at the possibilities. The 2020 change was simply released on Apple's website without any fanfare if I remember right. I think people were okay with the minimal changes since it was very low key.