Canada

Well on the flip side the LPC grassroots supported STV, and had twice in the previous ten years voted to make it party policy. I see no reason the LPC, majority in the house and elected to a mandate, should have been the ones to abandon their party policy for the policy of the smallest party in the house. But even then, in committee the NDP didn't recommend a specific form of MMP, they more or less provided vague instructions for choosing a new system, not a new system. The NDP also sided with the CPC, and reccoemended a referendum that could not be held before the next election. It was a bad spot, with no good way through.

MMP is difficult to explain to anyone uninterested in electoral reform, ie the majority of voters. Include things like party lists and members at large, and you can get some pretty significant drawbacks. There was also the more likely possibility of constitutional issues than with STV or ranked ballot, given the seat allocations outlined in the constitution.

Ranked or STV are easy to explain, ranked especially. Ridings and the ballots don't even need to change. Instead of an X, put numbers in the circle. Easy-peasy to explain.