It really is "a big deal" for several reasons.
1. This isn't a board exam, and without feedback on exactly which questions you got wrong it is more challenging to make improvements in your specific study habits. So you find out you got a phys question wrong? So what? Was it a question you were 90% sure you were right on, or 50%? Was it a second, third or fourth order question? So much detail is left out without actually seeing the question I don't feel like this needs further explanation. There is a reason every single board exam prep question bank gives you answer explanations.
2. No accountability for poorly written/wrongly keyed/ faulty questions. If a professor writes a question, they should be able to explain why the answer was correct and defend it, otherwise they are accountable to no one. Do you think when you give an answer on rounds you don't have to defend it?
3. The way this was handled was also very poor. The school administration has a responsibility to their students to treat them professionally and respectfully. To think they can just railroad their student body with any change they see fit just because "we've been doing it for 20 years" is ridiculous. Age and experience are not a guarantee of innovation and efficiency. We are scientists, back up what you claim with evidence and we will get behind you.
4. Medicine is continually changing and a change like no test reviews only guarantees the professors won't need to write new questions and will be able to re-use all their old questions without having to write new ones nearly as often.