This is an interesting topic, and one I wish I understood better. (I’m still looking for that reference book.) My understanding is that in the 19th century, the Bill of Rights was often thought of as a list of restrictions on the federal government. State and local governments had a lot more power and weren’t necessarily bound by these amendments, and even if they were, the federal government didn’t necessarily have the capability to enforce them.
The pendulum has very much swung the other direction. The 14th Amendment clarifies equal protection under the law, we have a history of court decisions upholding our rights, and the federal government has a myriad of law enforcement branches. From a 2A perspective, the big issue today is making sure the various amendments of the constitution are upheld equally. Courts generally like to err on the side of citizens with regard to the 1st, 4th, or 15th amendments, for example; we would simply like the same consideration for the 2nd.