Most people's ideas and worldview get basically frozen in time when they reach 25. Maybe not everyone, but a large enough majority that a death-free society would be effectively stagnant, socially and technologically.
Not by choice, in most cases. N.B. There's also a lot of research on restoring neural plasticity.
Seems many invent at an old age. Also seems that some few are responsible for great many breakthroughs, only stopping at their death beds...