> If pleasure is its sole motivation, it will prioritize it over survival.

Which is why I proposed a design with no pleasure construct.

> If the AI can't change its own motivation (its utility function) it's nothing more than a clever automaton.

The utility function is the way the mind decides which states of the world are desirable. You don't need to be able to change that to be intelligent. I'm unable to change myself so that I consider my family being murdered to be a good thing, but that doesn't make me 'just a clever automaton'.