samādhi means focus, it is the second of the three trainings, which are:
sīla - ethics or morality
samādhi - focus or concentration
paññā - wisdom or understanding
samādhi is a way of referring to meditation in general, so it is important at all stages of meditation practice. What is most important, though, is cultivating the samādhi that will lead to paññā.
There are certain types of samādhi that don't lead to paññā. The Bodhisatta practiced many of these many lifetimes and never became enlightened. Eventually he found a way of applying samādhi in a way that leads to paññā and that is what he taught. The other ways of meditation that don't focus on cultivating paññā are not important.