Why did God have the temple destroyed and Israel scattered among the nations?
God destroyed the temple and scattered Israel to confirm that believers are no longer under the Law and to remove any temptation to continue temple worship. If the temple and priesthood had remained viable, Jewish opposition and the sole place of worship might have prevented Christianity from getting off the ground.
Les explains that Jesus' words were mostly to people living under the Law. To make it profoundly certain that believers are no longer under the Law, God prompted the Roman Army to destroy the temple. If the temple had kept operating, Christianity might never have gotten off the ground because of profound Jewish opposition; the temple and priesthood were still viable and viewed as the only place to worship. So God had the temple totally destroyed, the priesthood uprooted, and Israel sent out into the nations, so there was no temptation to hang on to temple worship. Since the death, burial, resurrection, and revelation of the gospel of grace, Paul says henceforth we do not know Christ after the flesh and are no longer going by what He taught Israel under the Law.