Anyone with experience in politics knows why the Liberals did what they did.
IF the Liberals had pushed through the legislation, the CPC and Bloc were both going to portray it a Liberal power grab, and that message would definitely get traction. The CPC had already said they'd revert back to FPTP, and the Bloc was making noises that they'd back them up.
That's why the Liberals went out of their way to do what they did. What they didn't expect was the NDP going all or nothing on MMP, a system that laypeople find difficult to understand, and certainly not one to be explained easily in a sound bite.
Internal Liberal polling, not the dog and pony online poll, found that most people didn't care, but could easily be convinced it was a power grab. They were putting a lot of effort in something that had no upside, but a pile of potential downside.
They cut their losses, and aside from online forums, paid little price for it.