No single GPU is "overkill" for 1080p resolution as no single GPU can completely max every single game on the market. Those who have the money and want the absolute best performance will buy a single card that has the best specs... and even if there were a card that could completely max/60-120fps every single game @ 1080p, you also have higher requirements of games in the near future.
Buy the best you can comfortably afford if you want top performance. Personally, I wouldn't consider anything under a 4GB 770 or a R9 280X... and even then I would set those cards up for SLI or Crossfire in the near future.
"If you can't beat them, arrange to have them beaten" -George Carlin