We do indeed take that duty seriously, but the purpose of that bit of text was more of a sop to a losing side in the Constitutional debate, that wanted to depen

We do indeed take that duty seriously, but the purpose of that bit of text was more of a sop to a losing side in the Constitutional debate, that wanted to depend on militias instead of formal armies, which everyone agreed were a long term danger to liberty. People like George Washington convincingly argued from their Revolutionary War experience that militias weren't a complete solution. Needless to say, like the Revolutionary War smoothbore musket (not necessarily as useful for hunting as a slow to load back then rifle), today's "assault weapons" are the arms particularly suited for that duty.