Update: Lant Pritchett has kindly responded to my invitation and posted his thoughts: "No need for unmet need." Check out the comments section.
A quick look at the burgeoning literature on policy evaluations will reveal a preponderance of evaluations of demand side schemes such as conditional cash transfers. There is an obvious reason for this beyond the promise that such interventions hold: the technology of treatment allows for large sample randomized evaluations, either at the household or community/village level. As long as financing is sufficient to sample an adequate number of study units, study power will not be a concern.