Wartime command structures: Why are we so bad at designing effective ones?

I recently spent several hours trying to make sure I
understood who the American commanders in Afghanistan have been since 2001.
You'd think it would be simpler than that, but there were questions: Was
Hagenbeck ever in command of the entire American presence, or just of part of
it? When did Franks turn over country command to Mikolashek? Or did he? Are you
sure?

And that was the easy part. Next, try to figure out the
command structures -- NATO, ISAF,
American conventional forces, Special Operators, etc. What a mess.

But not, I further considered, unusual. Schwarzkopf had a
screwy command structure in the 1991 Gulf War -- like, why is the ground
commander 400 miles from the front? Westmoreland had problems in Vietnam. He
was not the theater commander, as best as I can make out, but commander only of
American ground forces in South Vietnam. And MacArthur divided his forces, had
his chief of staff dual-hatted as a corps commander.

It makes me wonder if there is a good book on American
command-and-control  structures in
modern times. If not there is a good dissertation to be done. If you do it,
maybe also include World War I.