In July 2020, the Perseverance rover launched on an Atlas V rocket and started its journey to Mars. In February 2021 it arrived and landed on the surface.
Imagine a manned mission to Mars, where a group of people would have to spend 7 months in interplanetary space. They would need food, water, and electricity that entire time. They would also be bombarded by significant amounts of radiation from the sun.
Imagine if we could get from Earth to Mars in 3–4 months. What if we could get there in a few weeks? Nuclear propulsion could make that a reality.