That pretty much describes all the social sciences. A morass of non-reproducibility, lack of controls, cherry picked data, bias, and subjective conclusions.
In this case, Maslow's work isn't even science.
philosophical
I feel like any research into this would be purely hypothetical? How would you even test that?
See if it rigorously predicts people’s priorities absent of the listed steps?
It's possible it's supposed to be normative though, obviously people don't run decision theory directly on the output of Solomonoff induction using a pre-programmed or learned utility function, but it's what they should do (but they can't, because it's not even computable). It's the theoretical perfection that all practical systems should attempt to approximate.
Same here. I find it relevant because it creates an awareness of where I am in my current state of mind. I also think I can derive a morality from it, or at least some personal values of mine. I don’t know how to describe it properly, though.