Hovering a rocket under controlled conditions and actually recovering a rocket stage that was used operationally are fairly different. It seems as though they've put most of the pieces together in terms of proving they can reuse the first stages, but they haven't actually done that operationally, and there are still many doubters (even in this very thread). Actually bringing the first stage back is one step closer to proving they can reuse the stages, which would be a tremendous step forward in spaceflight.

Similarly, Apollo 8 and Apollo 10 proved fairly conclusively that NASA could land humans on the moon, but it was actually doing so on Apollo 11 that was so incredibly important.