What did OEMs expect?
They have been flat refusing to build the devices Google wanted to be offered. Lead, follow or get out of the way.
Uniquely Pixel features: Google can add their own special sauce on top of Android just like anyone else can. There is nothing wrong with that. If the other OEMs find that Google's unique spin is popular they will no doubt copy it. Goodness know most things they do to stock Android subtract, not add, value.
And that is the problem. To make their Android products unique they take away from the smooth integration their products could have.