It should be noted that the Jews’ punishment for committing the sin of idolatry in the story of the golden calf was less severe than the punishment they later received in the incident of the scouts (when the people did not want to go to conquer the Land of Israel; see Numbers, ch. 14). This demonstrates that idolatry is a lesser crime in God’s eyes than an unwillingness on the part of the Jewish people to build their own state in the Land of Israel.
In creating the calf, although the Jews made a truly serious blunder, they were not giving up on themselves and their future. They were bewildered, not knowing what to do; they needed a leader to go ahead of them and show them the way. Because the calf was meant to replace Moses, not God, their crime was not deemed all that horrific.
After the punishment of the participants in the sin of the calf, the people as a whole survived and moved on to the Land of Israel. Aaron did not forfeit his priesthood, nor did the Jews lose their chosenness. Simply put, it is a story of ordinary, and excusable, human error.
But the Jews’ refusal to conquer the Land of Israel, in the incident of the scouts, brought far worse consequences, because it meant that they were refusing to fulfill their mission of bringing Divine light to the world. Indeed, that mission can be realized only when the Jews are a true nation living autonomously in their own state, the Land of Israel. And so, their refusal to realize that mission led to the death of an entire generation, the “generation of the wilderness.”