Why voter turnout is lower than... well, something really low.
So, why should we abolish the Constitution? Well, pick your issue. School funding, government over-spending, campaign finance problems, environmental issues, unsubsidies? All of these have huge problems directly caused by our mode of government. What's more, they aren't issues just one side would support (like, say, gun control activists or pro-lifers), but things any member of any political party would see as needing to be fixed.
The most important issue though is what our Constitution does to public apathy regarding politics. I'm not just talking about voter turnout (although that certainly is a key indicator), but the detatchment and disgust almost any American citizen feels regarding their government. There are two problems that any complex political process foists upon us, and until we adopt a simpler system of government, they will remain a burden on our backs.
1) Splitting power. If you're reading this, you probably consider yourself an active participant in American democracy. You know who the Cabinet Secretaries are, who your Congressman and Senators are, who controls your state government. Okay, so what committees do your federal representatives sit on? Who are your state senator and state representative? What are the machinations of your state political party? Heck, what was in the president's platform regarding education funding last year? These are all very important things that the idea of "democratic accountability" assumes you are paying attention to. Because if even the political junkies of this country aren't paying attention to these things, most people certainly aren't, and so much else else goes down the drain after that. Special interest groups, yellow dog partisanship, pork-barrelling, you know the whole schpiel. It's often lamented as the root trouble with our country.
But ask yourself: why should anyone HAVE to know all this (let alone, everyone)? How can members of a republic be expected to be a watchdog for their state governments, their local governments, their federal executive branch, and their federal legislative branch? So they aren't. Why remember a President's platform, when he has to get it through Congress anyway, and is as likely as not to be railroaded by members of his own party (ala Tom Delay or Ted Kennedy)? How can we hold our Congressmen to their promises regarding education, when their hands are tied by the fact that the Constitution says this responsibility is solely the states'. So the simple answer is: we don't. The public doesn't ignore political news because they don't care about these issues, but because it's a bysantine process that no single vote can affect.
In all of the industrialized democracies, you know what the only country that has voter turnout rates as low as ours (50% and falling) is? Switzerland. You know what the only other country that has as complex a government, with regional "cantons" that each need to individually vote affirmative for a major issue to pass? Just guess. People aren't going to get involved if there is no direct way of changing their government.
2) Political maneuvering. Politicians who dedicate their life to improving the world have no inate desire to pull every trick in the book just to get their way. California Recall, impeachment, lawsuit acitivism, filibustering presidential nominees, finding loopholes in campaign spending limits, constant redistrictring. These are amoral plots that would wear anyone down, and have little to do about finding out what most people want - and simply enacting it. But offer anyone a special strategy, and if they truly believe in their cause, they'll HAVE to jump at it (if they wouldn't, their supporters should find someone who would). It's like accidentally putting a loophole in the tax code, and expecting honest people not to take advantage of it. Of course they will. Should we expect any differently of an elected representative who's spent many years trying to promote christianity and associated values in America, to ignore an opportunity to filibuster an amendment regarding God in schools, even if the majority of America oppose him? Or a inner city Democrat, preventing child care cuts? They'll take whatever tools we put on the table for them, and they are honorable souls for it.
But these types of political scheming is a constant gridlock, that forces us to pay for the court costs, election costs, media converage of irrelevant issues, and a bloated political infrastructure. In applying equally to both sides, it produces nothing but inefficiency. Without these tricks, with only simply majorities ruling on any issue, politics would be less about committee Machiavellians and more about public debate over serious issues. Should the government position on affirmative action be decided by public discourse and relevant voting, or whether the Senate Republicans can manipulate rules to break the Democrat's filibuster of Charles Pickering? If political decisions are decided by the latter, is it no wonder that we have a government that holds up biased Civil Rights Commission decisions on one hand, and flies pictures of the Confederate flag on another. This will not do.