I think that political calculations regarding proportional representation were a factor in the Liberal decision to scrap reform but the stated reason for not wanting a MMP system is a pretty good one. In Europe MMP has supported a lot of fringe parties that have used the funding that comes with having full-time representatives on government payrolls to build strength to the detriment of the political environment.
Folks cite the fact that fringe parties only receive 1%ish of the vote in Canada as evidence that this is not a valid concern but it is easy to see how voter behaviour would change as campaign mechanics changed due to a PR system. (These arguments rather conveniently ignore the number of Green Party votes that Canadians in most ridings cast knowing they are throwing their vote away when arriving at the 1% number.)
Folks cite the fact that fringe parties only receive 1%ish of the vote in Canada as evidence that this is not a valid concern but it is easy to see how voter behaviour would change as campaign mechanics changed due to a PR system. (These arguments rather conveniently ignore the number of Green Party votes that Canadians in most ridings cast knowing they are throwing their vote away when arriving at the 1% number.)