To be fair Illumination only has made two good films (DM1 and Sing, have yet to see Grinch). The rest are either mediocre to garbage.
That said, I don’t believe the kids who enjoy are suffering as every generation is nostalgic to something no matter how bad it is (again I don’t get why some of my friends are so fond of Shark Tale). Besides families, kids and a good amount of the GA like them, and their approach works far better than other studios as evident through box office so they’re aren’t talentless. However if their films were better, they could do so much more.