The same guy that ran the Brexit campaign successfully convinced people that 'wasting' money on more democracy would lead to more dead babies and soldiers. Too many ironies there to list.
Another reason why it lost was because a lot of proponents of PR saw it as a trap to get electoral reform off the agenda. Most people in the UK I know who supported PR voted against the change for that reason, and considered accepting it as part of the coalition agreements as a total betrayal by the Liberal Democrats.
I doubt this subset of a subset of voters had any meaningful impact on the result. The only political parties to espouse this view were the (very small and fringe) BNP and Respect parties.
I can imagine a large chunk of people were in the "would have preferred to vote for PR, but still voted Yes to AV" camp though.
None of the people I discussed this with would ever consider either Respect or the BNP. They were Labour or Lib Dem voter. It was a widespread sentiment in my circles.
I think you're massively underestimating just how many people were angry about it. I know people who voted Lib Dem over their promise of PR who have woved never ever to vote for them again.
