Well, actually, Harper was elected on roughly 23% of the vote, and Trudeau got a majority on 27% of the vote.  The big problem is turnout:  When Harper got his majority, turnout was only 52% of eligible voters.  For Justin Trudeau it was 61% of eligible voters.

By contrast, from 1921 to 1993 it was typically 68% to 74% of eligible votes.

When we got rid of door-to-door enumeration, turnout crashed.

When the Conservatives brought in voter ID, it took another drop down.

Now, since voter ID, roughly 22% fewer votes are cast in federal and provincial elections than previously, relative to the total potential voting-age population.

Lack of turnout has a huge effect on the legitimacy of the outcome of elections.

Other than abolishing FPTP, the most important thing we can do to rebuild the legitimacy of our elections is to bring back door-to-door household enumeration.