You mean the American ones? They made a right dog's breakfast of it, actually.
They should not have excluded so many people
They should have included more safeguards against fraud
They should have restricted states rights
So, the different states had different election rules, and levels of popular representation.
And, of course, the splitting the country into slave / free halves was a horrendous blunder that not only led directly to the biggest slaughter in US history
And even more of disease in the aftermath.(by comparison, 405, 400 were killed in WWII, when the population was ten times the what it was 1860. Meanwhile, the wretched existence of enslaved people resulted in immeasurable suffering, which continues today.
Maybe so, but they seemed more interested in a strong, economically successful federation that could stand up to England and Spain than the welfare of the general populace. To that end, they made disastrous compromises.
However, the amending formula did serve, over time, to mitigate many of the effects. (Which may be why some vested interests want to tear it up.)