She is too extreme of a messenger.
This is the part I personally take issue with, but I think most would consider me to be a chicken little. I actually think we're at a tipping point, and we're very likely to take the plunge on the wrong side. To me there's no way to be too extreme about this message, because in 50 years when the remaining 90% have finally realized how absolutely fucked we are, some percentage of them are going to screech 'why didn't you tell us louder!' to which I'll just want to scream obscenities at them.
The environmentalist movement has tried 'these are the facts, things are grim' from scientists, that didn't work. They tried 'love mother earth' from the hippies, that didn't work. They tried 'real talk, this is how we are going to die' from celebrities and more scientists, that didn't work. They tried 'here's all the dead animals at our feet, here's some videos of our environment collapsing, and here's the reflection on our weather and our economy' from every expert that can be found, and THAT didn't work.
So I say bring on the next generation, let them crucify the olds and implement some policies that might save their bacon. We (collectively) sure as shit haven't done enough to ensure they won't die from starvation in a few decades.