Disallowing the use of AI is basically the modern equivalent of testing based on memorization. It is a laziness to find something more useful to evaluate on or an inability to distinguish real understanding in a field from first level understanding.

Professors need to step up and teach value beyond what LLMs know (very possible with or without LLMS). Or get out of the way from those building on the field with LLMs.

If you’re teaching students something that LLMs can score 100 on you are not adequately teaching them something useful for them in the future.

If your score falls 50% from not using AI, that's not testing memorization. That's testing learning anything on the topic being tested. The quantity of information on college exams is not that much to memorize. At least, personally, failing to remember something was rarely a reason why I failed to answer a question. Almost always it was because I did not fully understand the topic, so I tried to fall back on remembering if I answered the same question before.