alt Hacker NewsThe difference is in cases where the parliament chooses the executive is it leads to it's own collusion and corruption in terms of excessively growing govt... not that it's barely held the US from doing so. The point is to be in an adversarial context in order to resist overreach of govt.
For better or worse, our system today isn't quite what it was originally designed as... The Senate was originally selected by the state govts, not direct election... the Vice President was originally the runner-up, not a paired ticket and generally hamstrung as a result. The VP didn't originally participate in the Senate either, that came after WWII.
The good part about the constitution is there is a reasonable set of ground rules for changing said constitution with a minimum that should clearly represent the will of the majority of the population. (corrupt politicians not-withstanding)
Almost every country ranked for having the least corruption is a parliamentary system. Actually proportional parliamentary seem to be even better in terms of little corruption.
The reasonable set of ground rules seem to favor states over the will of the majority of the population. It is possible to change the constitution with states representing only 25% of the population. And remember you'd only need a majority in each of those states so could be way less of the population.
Overall the system seems flawed in that instead of having clearly delegated areas of responsibility to states and then doing the federal system as based on the population of the whole country it muddled areas and then made a federal system that couldn't respond to the population.