is he saying that flawed perceptions from erroneous or politically skewed information should not drive decisions?

I suspect he like I knows that happens but bitterly regrets that it does. It isn't a question of wishful thinking, simply stating the fact that it happens, should not -- and need not. As he said, a lot of 'historians' write drivel -- and a lot of decision makers do not allow themselves to be swayed by 'information' (see Bush, G.W. for a recent example).

Take the Saigon Embassy and Tet, both discussed above but in the terms of the historian's views on them . Some of us who were around back then have a totally different take on the actions and reactions to them. While it is true that perception is reality, it is not quite true that Politician's perceptions are deliberately attuned to what they THINK their voters want, they are attuned to what the Politician personally wants and attributes to what his or her voters should want in his or her view.

I believe that and a few other aberrations are the issues Wilf alludes and object to...

Fuchs:
There's no way how a look at effect only (ignoring cost) could be superior to a look at efficiency.
Depends on your viewpoint or emphasis. Militarily to look at effectiveness is the only sensible option.

However, holistically and politically for the majority of circumstances you're certainly correct. Cost is, of course, always a factor and in times of peace or near peace it dominates. Frequently in times of minor war it is an inconsequential issue; it literally becomes a non-issue in total existential war or anything near it (like WW II) when military effectiveness and/or combat effectiveness (not the same thing) take precedence, occasionally totally.

The military professional should look solely at effectiveness for his plan and recommendation, the Politicians will then tell him what they will support and he must retool his plans accordingly. In many cases, there will be minimal constraint imposed by 'cost efficient' models and the effectiveness can and will rule what happens. If, however, one plans with an eye on efficiency (which entails giving costs undue emphasis), then one is likely to produce a flawed plan that will not be effective. I emphasize that in this respect, I'm speaking of financial costs only; impacts such as economy of force or effort, casualties, terrain or initiative lost or gained are in reality more an effectiveness issue, current and future, than one of efficiency.