Now, we all agree that bad politicans cause people to lose interest in politics. But people forget that the opposite holds too - voter apathy causes shoddy politicans. Say you're performing on stage in a band but the crowd is ignoring you.. would you give it your all? Likewise, If you're a TD and you knew that a third of the electorate had no opinion on whether you got elected or not, would you make a special effort to please those people? On the other hand, imagine we had a 95% turnout in general elections, and every time a TD reneged on an election promise there were riots in the streets. In short, politicians respond to incentives just like everyone else.
I also think that some voter apathy is just sour grapes in disguise: "The person I voted for didn't get elected. I didn't win, so I'm going to go sulk in the corner and not play any more."
Yeah, so we have a democracy, and it basically works. So use it. (Also, am I the only one in favour of Australian-style compulsory voting?)
Finally, a quote: "People who vote in Big Brother / Pop Idol / Eurovision but do not vote in parliamentary elections relinquish all rights to express any political opinions whatsoever."