To recap, the Second actually doesn't defend the right to bear arms. Rather it uses the right to bear arms to justify the formation of regulated militias.
The reason for this is that the right to bear arms is a natural right and thus does not require government approval. It's a natural right because it's part of the right to defend oneself and loved ones.
On the other hand, defending strangers (like fellow countrymen) is not a natural right and requires government enforcement. Ironically, that's where the Second comes in, together with Art. 1 Sec. 8 and the Militia Acts.
Finally, natural rights may be abridged by law for one reason or another. Hence, government units may impose gun control. In turn, citizens who are against this may vote for government officials who do not support such.