PM Trudeau did the right thing by changing his mind about changing the voting system. I'm assuming you mean changing it to proportional representation which would facilitate the election of extremest, single issue candidates,  regional separatist parties, or loony left or right wing parties that could hold the country ransom in a minority government situation. 
Parliamentary democracies and big diverse countries in general  require big tent parties for stability. Obviously Mr. Trudeau's advisers reminded him of this and convinced him to backtrack
on a promise he never should have made in the first place.