Fifty years old is "out-of-date". But 250, not so much.

[jmg257]

16. Madison specifically refers to why he didn't propose any articles about standing armies...

even though several states wanted them. Madison knew that any restriction would be ignored if "opposed to the decided sense of the public":

"Supposing a bill of rights to be proper the articles which ought to compose it, admit of much discussion. I am inclined to think that absolute restrictions in cases that are doubtful, or where emergencies may overrule them, ought to be avoided. The restrictions however strongly marked on paper will never be regarded when opposed to the decided sense of the public; and after repeated violations in extraordinary cases, they will lose even their ordinary efficacy. Should a Rebellion or insurrection alarm the people as well as the Government, and a suspension of the Hab. Corp. be dictated by the alarm, no written prohibitions on earth would prevent the measure. Should an army in time of peace be gradually established in our neighbourhood by Britn: or Spain, declarations on paper would have as little effect in preventing a standing force for the public safety. The best security agst. these evils is to remove the pretext for them."

James Madison to Jefferson, 1788


Hence the security for ensuring effective Militias, to avoid the pretext for maintaining standing armies.

ETA: Of course that never turned out as well as the founders hoped, as not too many took the duty/right of bearing arms all that seriously.