I am a huge fan of Zinn, and have read other books in the people's history series. Vijay Prashad's People's History of the Third World is amazing, if you haven't read it. I also think it is totally fair to critique a generation, if their decisions are a net negative. Each generation has a responsibility as far as future generations go. That doesn't mean every person in that generation is to blame, just like it isn't fair to blame every American when our government does something. However, I think it's fair to say that the collective decisions they've made will have a negative impact on future generations.
How are things worse?! The environment, for one, is in a state of collapse. There is a multi-trillion dollar infrastructure gap. They used to have an economy that produced decent jobs for working people, isn't the case anymore. They lived in an more economically equitable society. There were also important civil rights victories, which have not built on but whittled away. There wasn't anything like the WTO, or NAFTA like deals. There was the GATT, but that was radically different than the WTO. Real wages haven't grown in decades, inequality has exploded since Reagan, as has financialization, student loan debt is massive, on and on. The war on drugs has destroyed communities of color, as has deindustrialization, school privatizations, predatory finance, capital flight from the cities, the militarization of the police.the wage gap between white and black workers has grown in recent decades and the black community in particular was destroyed by the crash in 2007. Throw in the fact that both political parties have moved to the right and are thoroughly corrupt, there is little hope right now within the system. There have been some advancements, like marriage equality, but on economic issues, environmentally, with infrastructure, politically, socially, things are falling apart.
I respect a lot of people in that generation. I am just saying that it's time for everyone to think critically about how we got here.