Do lawyers have a moral oligation to blog? Yes.
"The American Bar Association Model Rules of Professional Conduct and a number of states have ethical rules & guidelines saying a lawyer has a moral obligation to engage in public interest legal service.
Traditionally this has meant pro bono cases, accepting appointments, membership in legal services organizations, law reform activities or involvement in nonprofit and court-annexed limited legal services programs. But why not providing public education on the law as a way for lawyers to meet their moral and social obligations?"