Fundamentally flawed ...hmmm. Well it sure wasn't handed down from on high, like the Ten Commandments were. If the US Constitution were divinely ordained, then it would never need to be fixed. As it is, however, it was written by inter alia merchants, trading with the enemy, land dealers, stealing land from the Crown, and other speculators - none of whom saw any reason why they should pay for the defence they had sought from Britain, and all of whom were ready to get the French, Dutch, Russians and Spanish to fight their wars for them.
(Yet look how America sneers at Europe now, and the French especially.)
There is nothing sacrosanct about ANY part of the Constitution, and, indeed it has already been amended many times, and even some amendements have been amended.