I agree that too many in the country don't exercise their right to vote, but I wouldn't take away their right to abstain. But, I mean, that could be solved by having an `abstain` option on the ballot itself.
Here in Australia it's mandatory to "vote" or you get a crappy little fine, few hundred, who cares. But here's the clever bit, voting just consists of showing up and giving your name so they can cross you off the list. You can take the ballot, and just shove it in the box blank. Perfectly legal "abstain" vote in a country where you have to vote.