Israel's desert experience, as described throughout the book of Numbers, is a reality created by G-d in which He tends to their every need.
At the same time, He teaches them how to take responsibility for themselves as individuals and also as a nation.
When they shy away or shirk their responsibility, G-d rebukes them.
In this manner, they are being prepared to enter into the land of Israel where they will assume their role in bringing the entire world closer to G-d and His Torah.