For me it is standover (important if you spend lots of time standing over your top tube, but not for much else)....
It's also important if one comes down hard on the top tube.
and saddle width (for me saddle comfort is much more important than width).
I agree on this. Most people riding road bikes rest on their pubic rami, not their ischial tuberosities.
People seem to focus on these 2 aspects of fit at the expense of getting saddle height, saddle fore and aft, and bar height correct....
Where do you see that? I see lots of questions on saddle height and some on saddle fore and aft.
...I see lots of people on bikes that are way too small for them (and with long seatposts and raised bars as a result) on the basis that they need more standover than a bigger bike can provide.
Is it the standover propaganda or is it that racers ride small bikes, and buyers want to look like racers? I strongly suspect it's the latter.