One Generation cannot bind another?

http://teachingamericanhistory.org/library/document/letter-to-james-madison-17/

This made the front page of Reddit the other day. One of our founding fathers believed it was wrong for any one generation to bind future generations by rules, and wanted the Constitution, which is currently held in the highest regard as a legal document, to expire every 19 years.

After watching United States of Secrets, I am very, VERY happy that this is not the case. While the government basically managed to circumvent the rules in place, the Constitution was the one legal leg any dissenters in or out of the government had to stand on against The Program, including the modified Thinthread, Prism, etc. If the government had the ability to rewrite the fundamental rules they had to follow every 19 years, I fully believe the US citizenry would have many less rights than they do now. After 9/11 the Bush administration could have used the terrorist panic to completely rewrite the Constitution, giving the NSA unlimited power entirely legally, with no worry about the justice department having any way to stop them.

Still, the idea that previous generations shouldn't bind current generations is not a bad one, though in the case of the government I believe it's rather a case of moral people binding amoral people. I think it might be good in the long run if the Constitution was a malleable document, though. The ability to rewrite certain things to be more modern and relevant (*cough cough* the second amendment *cough cough*), overall I think having a static backbone to the structure of our government is a good thing. If you can't tell, I'm not very decisive on this matter because I have a poor legal background, but this topic is really interesting.