For the most part, enhanced communication does not really enter into the issue of whether it is better to have different criminal laws in different states. Most crimes are committed by people in the state where they live and they do not think about whether it would be more beneficial to them to commit their crimes in some other state where the penalties would be less severe. For such people, the presence or absence of national standards is irrelevant.
For some people, but only for a very few, the presence of different laws in different states could matter. People who are going to commit things like financial (white collar) crimes might move to states where such crimes are punished less heavily. This would argue for a national standard because it would make it impossible for people to “shop around” for places where crime is less likely to be punished.
Overall (without regard to the idea of advanced communications), the major benefit of having one national standard is that it is fairer for everyone. There is no reason why the same crime should be punished differently in different states. It is, arguably, unfair to a person to be punished more heavily for a given crime because of where they happened to commit that crime. The major benefit of having state standards is that it allows different states to be more responsive to the demands of their people. It allows for cultural differences in attitudes towards crime and punishment.