This is amazing. It's equivalent to the stepping stones the Gemini program accomplished in the bridge between the Mercury and Apollo lunar missions. You had to prove you could stay in space a long time (eating, sleeping, drinking, etc - many doctors thought humans wouldn't be able to do that), that you could go outside the capsule, that you could rendezvous with another vehicle, that you could dock, that you could change trajectories, control your reentry.... this is a stepping stone like that. Being able to control the descent of a booster like that and catch it provides a foundation for building blocks to an eventual mars mission and perhaps moon stations. NOt just about being able to quickly turn around a booster for another flight but to provide the precision needed. This was a big deal.