The period of time that Am Yisrael spent in the desert was parallel to the time of Yenikah (suckling) in the upper realms. The manifestation of this on earth was that there was a high level of intimate contact between Hashem and Am Yisrael. When there was sin, punishment was many time in the form of open miracles and a departure from the natural order.
In our day, at the end of the period preceding Yemot HaMoshiach (Katnut Beit), it is not proper to expect this level of direct intervention, for we are at a more advanced stage in human history.
As a result, when studying the lessons from Dor HaMidbar to apply to our life today, we should not just say "and then Hashem smites them!" or anything else simplistic. That does not mean write Hashem out of the lesson, chas v'shalom. It means care must be taken with this analysis.