Just the fact that you've been at a given company for a while might be enough of a reason. Even if everything is going well you might want to find out how life looks somewhere else; you can usually come back if it turns out worse, so why not?

I think the thing about life is that its complexity can't be reduced to a list of criteria.

Sure it can. That list will just be different for different people.

And that's the author's point. He's not trying to declare the official list of criteria, but just point out that, subconsciously, you do have one. And one small change to one value in the decision matrix might be the tipping point to entertain job offers.

The sooner you become consciously aware of it, the better.

Different for different people, different for different points in time for the same people (e.g. when parenting arrives)... Modeling life is hard. :)

Nah, you'd expect Life to be at least Turing-complete.

Parent obviously meant a list of specific criteria applied to everybody.

Not to mention that your answer implies that people only do things because of some list of personal criteria -- e.g. that they always take conscious and/or rational decisions.

Having a voice and starting something new in the world, instead of being a replaceable tiny nail in a mansion built by someone else.