It's not that complicated, actually. In the guise of glorifying an "older" woman, this movie perpetuates poisonous assumptions about women—young and old—and what's acceptable in their dealings with one another. And I don't know who told Meryl Streep she had a great laugh, but that person should be shot. She just won't stop!
And to prove my point, I tried laughing at approximately the same intervals and looniness in my own living room, and it totally freaked my daughter out. It actually frightened her. She begged me not to do it anymore.