It is unfair to call this process rigged. 

Political parties have the right to select who they want to represent them. Anyone who does not get the nomintion can stand for election as independents. The only difference is that they do not have a national brand and established party organization to back them up.

In the case of the Markham Thornhill riding it is my understanding that the rejected candidate was planning on rigging the nomination herself by flooding the local party with new members who would naturally support her. Hardly what you would call fair.

I recall something similar happening in Barrie a decade ago. A local special interest group tried to get their favourite nominated. The national party had to step in to stop this.

There is no good reason to change the current system which actually prevents the nation brand of a party from being hijacked by special interest groups.