In the long term, when people just accepted voting as a matter of course, it might provide truly representative Parliaments etc. But in the short term, many people who resented being forced to vote might vote for oddball parties or in other perverse ways; and we might have some strange election results. Frankly, I'd rather being governed by local and national Govenments chosen by people interested enough to vote voluntarily, even if that is a minority of the electorate.