I think it's a bad policy on the merits. In terms of gender roles, I don't think that it's a good call, and even in countries such as Israel which, as a matter of resource necessity, have historically included women in conscription, it's generally been found that actual infantry combat units function best when all male.
However, I'd argue that it's an empty gesture either way, because it's unlikely that the draft will serve a purpose in any future American war.
From the total French mobilization of the Napoleonic Era through the World Wars, major powers fought wars of national mobilization. Even as technology and mechanization changed the face of war from 1800 to 1945, the ability to put large numbers of riflemen in the field remained a major factor in fighting and winning wars. This is why major powers established systems of conscription. In France and Germany, there was actual universal conscription. Even in peacetime, the majority of young men spend 2-3 years (usually starting at age 20) in uniform as full time soldiers. They drilled, received weapons training, and took part in full scale wargames -- all this designed to assure that at any time the country could mobilize a large number of men who had received several years of military training at some point withing the previous decade. The US and UK did not have conscription, and had only small professional armies, but both instituted a draft during each world war in order to fill the ranks of the army with the millions of young men needed to field a modern army.
Of these mass armies, a large percentage (larger in WW1, smaller in WW2) were riflemen. However, even as the major powers were fielding the largest armies in history during WW1 and WW2, technology was advancing in ways which would gradually take the emphasis away from battles between massed riflemen.
The famous aspect of this involves flashy big technology: modern artillery, tanks, airplanes, helicopters, etc. However, even among infantrymen themselves the degree of specialization had increased tremendously. For example, in 1914 a French infantry platoon consisted of 60 men: 1 lieutenant, seven non-commissioned officers, and 52 riflemen. All of those riflemen carried the same equipment and were trained to fight in the same way. By 1918, however, that platoon had been reduced in size to 30-40 men, and rather than being an undifferentiated mass of identically armed and trained men, they were organized into different combat groups with different weapons and purposes: machine gun group, rifle grenade group, bombing (hand grenade) group. A fully trained set of combat groups functions as its own small combined arms force.
In the hundred years since, the infantry platoon has become more differentiated, more mobile, and far more lethal. This is a result of both technology and the specialized training which the professionalization of the US Army since Vietnam has allowed. As the amount of firepower that a small group of soldiers can lay down has increased, the need for huge masses of men has decreased. A modern squad of nine infantrymen can lay down more fire than a platoon or perhaps a whole company of 200+ men a hundred years ago. And with a small number of men able to deploy such a huge amount of fire, having large masses of infantrymen is actually a battlefield liability: a bigger and denser target.
The fact that technology and training have overtaken numbers as the key factors in combat can be seen in recent wars that the US has fought. In the Gulf War, the number of soldiers deployed by the coalition was only slightly larger than the size of Iraq's army, and in the Iraq War, the number of US and allied soldiers in the initial invasion was actually, on paper, smaller than Hussein's army. In both cases, however, the US and it's allies won massive, lopsided victories. An army of conscripts equipped with cast of Eastern Bloc weaponry was nowhere near a match for the training and technology of the modern US Army.
The two wars against Iraq are easily portrayed as between a large power and a small one, and as we can see by the results Iraq was by no means a match for US military might. However, in terms of army size and equipment, there aren't a large number of powers in the world that have larger conventional military capacity than Iraq did. Setting aside nuclear weapons (as one certainly hopes any future war would) there simply isn't a potential future foe which the US would need to institute a draft to fight. Not only do we have a vastly larger military technology edge over any future foe than we did in past major wars, but we maintain a much larger peacetime army than we did during back when we tended towards disarmament between wars.
If we did become involved in a major war with another great power, we might need to massively increase our purchases of military technology, but the number of soldiers we'd need to recruit would be comparatively modest. Since our superiority as a military power relies so heavily on both technology and training, drafting large numbers of short term recruits would arguably be counter productive, failing to give us the kind of additional manpower we would need.
As such, it would make more sense to abolish the selective service system than to add women to it.