In 1937 the constitutionality of the Social Security Act was tested in two cases. The discretion of Congress is not even reviewable by the courts. For the most part their purpose is to correct a government gone awry. But most would serve only to patch with Scotch tape, chewing gum, and bailing wire, where full restoration is the only cure. This would cure much of what ails our nation and render most of the other proposed amendments unnecessary.
Congressmen respond to pressure from the people.
Of course, many, if not most, of those in Congress enjoy the status quo. They do like to get on the popular side of popular issues. If nobody could come home with pork, there would be no more competition for bringing it home, etc. Also, presumably they all love their own State and want the best for it. The States could regain power, authority, and money lost to the misconstrued Welfare Clause.