That may be, but consider the fact that it occurred over 200 years ago. No one could see, prepare, or even comprehend what changes would happen in that time period.
Self propelled transports? Airplanes? Nuclear weapons? The Internet? Travelling to the moon? A global economy? Etcetera, etcetera. The list goes on.
While their goal was to create a "more perfect union," and that they did accomplish, but their moral practices were not suited for this major change of events that has preceded that era. (I mean, how would Ben Franklin react if he saw a lolcat?) They did however know that in order to adapt to the future, they would need to allow the constitution "flexibility" to ensure the lasting stability of the country with whatever the future threw at it.
We are in a weird time now yes, and there are many problems facing this country. Some that even threaten the coziness that we as fat-ass american have enjoyed this past decade. (Boo hoo!) Fuck it, bring on some reform, I welcome it as long it is practical and smart. But at this point in time we sit better as a country, than from most of what our short lived history has been.