I don't think people are really unhappy with the manifesto, but with applied Agile as it is experienced out in the world where you're having your workday ordered by high powered productivity consultants and LinkedIn-brained middle managers.
Manifesto is the one with a small a.
Big A Agile is an exercise in making management happy because they read about it on LinkedIn while having a poo. It usually involves paying several consultants a lot of money.