Sending the Meraglim Was For Moshe’s Benefit
Rabenu Bechaya notes that the word “lecha” (for you) seems unnecessary, as it would suffice to just say to send men. He answers that the word “for you” is used to indicate that sending the spies was for Moshe’s benefit, as his life was lengthened as a result of this episode for the next 40 years, while the nation wandered in the desert.
It had been decreed that Moshe would not enter Eretz Yisroel, and if not for the meraglim’s sin, the nation would have entered the land immediately and Moshe’s life would have come to an end. Thus, this story lengthened his life by 40 years.