If we were talking about handling the private signing keys I would agree with you. Different types of data have different levels of security needed. Over classifying trivial data just makes it harder to get things done.
Strictly speaking, If a user in a workplace where this behavior is against the security policy acts like this or expresses this opinion, namely, that they wont be stopped by a security policy to hold their presentation, they are a user group that arent just a possible attack vector but a possible attacker them self.
If your company forbids the usage of USB ports, they do that for a reason, whether individual users think that is reasonable or not. This isnt just about possibly leaking data, but introducing stuff in an environment that is supposed to be closed. Differently put, as a bad faithed person, I will gladly borrow you my USB Stick to transfer your important files so you dont get in trouble for having technical hickups. I also will take you up on the "thank you" snacks and will also watch silently when you get in trouble for intentionally breaking security policies and infecting the network.
The vast majority of people in an organization don't work with sensitive material. It makes much more sense to do this on a per department basis.
Policies like this that ignore on the ground reality and make it hard to get work done encourage abuse of the rules. When the rules are too draconian people will work around them and it encourages disrespect for other rules - especially the ones that actually do improve security.
Those rules arent draconian, someone somewhere was hired to make a risk assessment and found them to be necessary. You dont circumvent them period. Thats the responsibility of each an every employee. No matter if you think they are stupid, it isnt your call to make, except if someone hires you for exactly that, then they are your responsibility to do right.
Most attacks arent some espionage stuff, its plain and simply precaution against fraud and theft. And they target people who are to proud for their own good who never think of themself being at threat. Which is sadly something a lot of computer scientists have a bit of a problem with. No one wants to believe they could be duped like that, they surely would know it better. Security policies are there to not have to rely on individual egos and look at it more realisticly. Most of us will be duped when taken advantage of in a bad moment without enough time to think about it. Thats why people do it.
There is a reason even the CEO and CSO have to wear their badges. There is a reason a lot of Snowdens colleges started to get really scared once it became clear which credentials he used to access the files. And they were lucky, he could have been a criminal and sure as hell wouldnt have mentioned that those data leakages where his responsibility. He could have simply been a criminal transferring money in their names.
Meetings happen daily, an iffy wifi connection is enough to waste the time of everyone in the meeting (10 minutes x 15 people is 2.5 person hours). These mundane things happen day in and day out. Someone walking around with an audio based keylogger is dramatically less likely to happen (and this ban on USB drives wouldn't prevent that anyways).
If you ignore the cost of people's time then pretty much every security idea makes sense. But its not a good way to run a business.
They have to protect sensitive client data. Need to protect against illegitimate leaks of data. And the universal way that they communicate with clients, opposing parties, regulators? Email.
You can't force the SEC to accept your new encrypted cloud solution, nor can you require opposing counsel to use YOUR solution. And communicating with hostile parties is the entire organization's reason for existing.
"Simple and reasonable" IT approaches to problems frequently break down when faced with people whose job it is to deal with other organizations.