Well, that may be true. We can't know how all of the Founders would have responded to the strengthening of Federal power if they had lived in the reality of the 19th century. But these were mostly liberal men, which is why they created a liberal government that could not only improve itself but respond to new information and changing circumstances. The point is to remain true to the core values of a more perfect union, the blessings of liberty and so on. The Founders wanted us to be able to evolve and refine those values in the unguessable future. But the price of liberty is eternal vigilance. The power to amend the Constitution has already been used to undermine those values at least once and there's no reason to suppose it can't happen again.