what is judge calabresi major critism of the exclusionary rule?

Answer 1

That it is more than is necessary to ensure fairness.

He appears to be saying that there are less drastic ways to ensure that police follow Constitutional requirements, and that defendants should not get an advantage because police broke the law.

The problem is, other methods were tried for decades, and found to be ineffective at preventing police from abushing their power. So, while it's a bad idea to let criminals go just because the police also broke the law, it's the only semi- workable solution yet found to try and keep the police honest.