I think it's a great policy even if the returning game doesn't win. It gives a condolence prize to those that really wanted the 2nd place game and who knows, this is only the fourth RetroActive and the third public poll for the feature. We may see the trends shift over time depending on what games are paired up in the polls.
Having a 2nd place guarantee return could encourage people to vote for their preferred game in hopes that even if it isn't an obvious favorite to win their game could get a quick second chance.
Plus I think it adds to the excitement of watching the polls, though that may just be me.