There should be. In industry, we call those things CTFs, and there are both attacker and defender CTFs. My experience has been that they are extremely effective learning tools.
As far as they go, maybe; but I worry that people don't appreciate the limitations. Making sure that someone can't code up an exploit against your system in half an hour is absolutely essential, but it's not the only thing that matters -- a serious cryptographer is also going to be concerned about "two years of coding and ten million dollars of computing power" attacks, which can be safely disregarded in CTFs.
As far as they go, maybe; but I worry that people don't appreciate the limitations. Making sure that someone can't code up an exploit against your system in half an hour is absolutely essential, but it's not the only thing that matters -- a serious cryptographer is also going to be concerned about "two years of coding and ten million dollars of computing power" attacks, which can be safely disregarded in CTFs.