Thing we look back on like WTF?!:
- Slaughtering thousands of whales in Tasmania to make oil for London street lamps.
- Bleeding sick people to make sure the disease bleeds out of their body.
- The 1980s.

Things we will look back on like WTF?! in 80 years:
- Millions of people voluntarily poisoning themselves several times each day with cigarettes.
- Using oil to run cars, instead of synthesizing food.
- The 1980s.

Things we look back on like "Well done!":
- Kicking Hitler's butt.
- The discovery of penicillin.
- Invention of the telephone/instantaneous communication.

Things we will look back on like "Well done!" in 80 years:
- Compulsory superannuation.
- All that money thrown at making solar power affordable and workable.
- The discrediting of Communism

I could have come up with stacks more for a few of them. Feel free to throw in your own ideas. But if anybody says "The Iraq War" for the WTF in 80 years, I will violently disagree. It will be waaay too soon to tell how that's going to play out in just eight decades time. Seriously!