*cracks knuckles before starting typing*
I think there are dangers when people look at that kind of data but don't put the numbers in context. The election in 1996 have very low turn out but Clintion won the election by over 10%, chances are that lots of people stayed home because the outcome was a foregone conclusion. Clintion had the election wrapped up before voting on the West coast closed, why vote if you've already won? Compare that with 2008 when Obama has the chance to make history by becoming the first black President, being part of that potentially outweights the inertia of voting in an election where the outcome has already been decided.
But the overall pattern is that 30-40% don't vote, despite the voting process being made easier with greater access to postal voting that 30+% hasn't changed much.[Personally I'm against postal voting expect for those people who genuinely can't get polling stations, it's all very well people going on about voting being a civic duty etc. but when they want that duty to have miminal effort I think that's a better indicator of how civic minded they are.] What's wrong with the system that 30+% of people don't see the point in taking part?
Look at the UK, 650 MP's in constituencies that a supposedly to be of roughly equal population. To get an outright majority a party needs 325 seats, to win a seat takes about 40% of the vote and turn out is around 60% of the electorate. So in theory it would be possible for a party of take power with only 15% of the population supporting them. While it is incredibly unlikely that it would happen can you really call a system that even allows for that possibility democratic?
Changing the system from the inside is fine in theory, but when there's a moat, a minefield, razor wire, a 100 ft high wall, snipers and machine gun nests between you and the door then you are never going to get inside to change anything. And you're missing the point, the way that some election boundaries are drawn means that the party that is in the minority can never win, the outcome of the election has been decided before a single vote has been cast. So instead of endorsing a corrupt system by participating, do the opposite and actively don't participate. The only time you get people winning democratic elections with over 70% of the over is when the vote is rigged, by not voting you push the result closer to one that can only come about in a corrupt system.
See if this makes it any clearer http://thedailyshow.cc.com/videos/0adjfq/american-horrible-story---gerrymandering
Downs work isn't an oversimplification, he's correct that there is no rational reason for voting. There are two problems with the idea, firstly as I said you can only know if your effort was wasted in retrospect. Secondly it assumes people act rationally but it turns out people are nowhere as rational as they think they are, mass voting is really a form of mass self-delusion.
As for not voting, the message it gives out depends on the context. Low turn in Afghanistan would suggest that the Taliban had succeeded in intimidating voters. In the US there is no legitimacy threshold on voting but if someone wins with 100% of the vote but only a 5% turn out then it would impossible not to conclude that there is something fundamentally wrong with the system. And if you want to compare the US with Egypt or any of the other Arab Spring states, then Egypt had dozens of parties and candidates running all with different ideas and agendas. Compare that to the US where it's a two party system so it's a battle for the middle ground; 40% are going to vote Democrat regardless of the candidate is; another 40% are always going to vote Republican so politicians are chasing and appeasing the 20% so they become more and more alike, they whole system becomes a beauty contest instead of a policy debate.
It doesn't matter how many coats of paint you put on it, Management BS is still Management BS. Also I'm out of paint.
There is a problem with the "Don't bring me problems, bring me solutions" approach, if the solution isn't perfect than it can be dismissed without ever having to acknowledge that there is a problem. The first real step in fixing any problem is admitting the problem exists. Once you get people to see and admit the problem it becomes impossible for them to return to a postion where they can no longer see the problem.
Look at the Crimean referendum, those who weren't ethnically Russian didn't vote for three reasons; voter intimidation, a rigged election and an unwillingness to give the vote even a fig leaf of legitimacy. If all the non-ethic Russians had voted it would have been used by Putin & co as proof of a fair vote. If an election is rigged then the only rational action is not to vote, but like I said before people are rarely rational despite most elections in the US being rigged.
Slavery might have been made illegal but the Voting Rights Act has been gutted, so free but with no voice that's real progress towards equality.