I don't particularly care if the infrastructure remains usable, and I certainly do not want my proposed target areas to continue to function. The effectiveness of genocide depends on ones point of view. Now, I am not advocating genocide here, my original response was tongue in cheek.
However, if a person or group is going to engage in genocide then they need to be willing to see it to its logical conclusion, I don't know that I would ever be prepared to go that far. I am much more comfortable with applying the old cliche about bombing a group back to the stone age than I am about attempting to kill every man, woman, and child in a target group.
Looked at as a technology, the Neutron bomb is a pretty neat invention. If it does work as advertised I don't know why it would not be employed. It seems to present an elegant solution to the dilemma of post exchange radioactive contamination. Perhaps they are deployed and we don't know about it. Maybe we should ask Julian Assange, he seems to have access to just about every piece of classified US information around.