David and I agree that we would like constitutional rules that would facilitate political bargains between people with different political interests; as David puts it: "if you ensure voters are who they say they are, we'll let you register more of them." But there is little reason to believe that the decision in Crawford facilitates such political bargains. Indiana's voter ID laws were among the strictest in the nation without any corresponding investment in government programs that would have made it easier for disenfranchised persons to comply with the law's requirements. It's worth noting, as Justice Breyer points out in his dissent, that the Carter-Baker commission conditioned its acceptance of voter ID laws on the requirement that states also make it very easy to obtain photo ID's and that these ID's would be issued free of charge. Doing so would help ameliorate the predictable effect of these laws acting as the equivalent of a poll tax by other means.
If you want to create incentives to achieve the sort of reforms envisioned by the Carter-Baker commission, you wouldn't want minimal judicial scrutiny of the sort the Court adopts. Rather, you would want a more searching judicial scrutiny that asked whether the state compensated for the difficulties it imposed on particular groups by creating methods of ameliorating those difficulties. Knowing that harsh laws would be struck down unless ameliorating programs were put in place would give legislatures incentives to strike precisely the sort of bargain that David favors. In contrast, the form of scrutiny the Court adopts in Crawford gives legislatures few incentives to strike such a bargain, because majorities can adopt voter ID laws that disenfranchise a significant number of voters who would vote for the opposite party without fear that the courts will strike these laws down.