This is why you need new individual:
- to not be blinded by a vision of the past;
- to ignorer status quo;
- to see things differently;
- to bring creativity;
- to bring a bit of chaos.
They are rare, those who, among us, can cumulate experience and a beginner's mind.
Imagine if Einstein, Tesla, Newton, Mozart, Beethoven, Gandhi, Martin Luther King, Nelson Mandela, Disney, Steve Jobs, etc. all lived for another couple hundred years. Do you truly believe they would stop trying to disrupt the status quo? It only takes one person to disrupt the status quo. Generally, it doesn't matter how many people are against something. Nothing can stop a great idea when its time has come.
Einstein objected to much of QM. There's the history of the adoption (and rejection) of plate tectonics over much of the 20th century. Continued opposition to old-Earth geology, or biological evolution. The present conflict within physics over string theory. Likely others.
At some point, fixed mental models tend to get in the way, even if the minds containing them once made novel and useful contributions.
That and no one person is bigger than science, Even though Einstein opposed QM it kept making advancements. Imagine if Einstein spent even all this time opposing it, their theory would be even more rigorous and advanced. More likely we would have changed his mind at some point and actively contributed, why would a one time scientist be stubborn for many decades in the face of so much evidence?
Another, more optimistical way to look at life extension is that it is what neural networks are to genetic algorithms. Instead of randomized search for better parameters you get a more directed one (backpropagation). In other words, instead of waiting for the next generation to learn on the same mistakes previous ones made, we can skip this and transfer knowledge in the future much faster.
It all depends in what form the technology will surface, and what the people will use it for once it does. I am willing to bet it won't be all good, but also not all bad.