Excerpt from the Divrei Chaim blog:
The mission to Eretz Yisrael was not the problem; it was the potential solution. We already saw in last week’s parsha that Bn”Y were grumbling. There was the episode of the misoninim, the episode of kivros ha’taavah, Miriam’s mistaken criticism of Moshe. The wheels were coming off the bus. The problem facing Moshe was what to do about it… This is why Moshe decided to sent shluchim into Eretz Yisrael. Rav Nosson Ra’anan, R’ Kook’s son in law, explained that Moshe’s hope was that a taste of kedushas ha’aretz would have the needed impact.