hi, actually I am not very fond of the term XY problem, as I find it misleading in the sense it is an old and important problem of mathematical physics. It is true that xy with no other context could make one think of correlation, but here it's the absence of "correlation" that is emphasized.
I would call it a "WHY not X" problem ;)

cheers --stephan maybe I am biased, I used to be a theoretical physicist ;)