Congressional leaders and their agreement with the administration, or lack of it, have an important effect on the public's sensitivity to casualties.
The second question is more difficult to answer. Avoidance of casualties is an unassailably desirable objective. It is precisely the natural nobility of the argument that makes it susceptible to misuse in the policy-making process, potentially leading to ineffective or inefficient choices. The persistence of the myth also causes adversaries to misjudge the likely reactions of the United States. In both of these ways, the myth of deep-seated casualty aversion among the American public hinders the pursuit of American national objectives.The conventional wisdom is strong among civilian, military, and media elites. Steven Kull and I. M. Destler have recorded many interviews-with members of Congress and their staffs, the media, the executive branch, and leaders of nongovernmental organizations-that support this view.3 Other interviews with members of the media and military leaders also confirm a widespread belief that the American public is unwilling to accept casualties.4
If the myth is believed by enough people - enough to affect public policy - it is no longer a myth but reality. The article you cited seems to confirm that the myth is no longer myth.