This is a great question.
As an academy student, we are required to learn all of the codes. Some of them are ridiculous. For example "11-15--Ball game in the street." Now why in the world do we need a code for that? How often is that actually used?
BUT, there are some codes that should be kept because they are useful. For example, here, 10-16 means "prisoner." So if you are alerting your cover officer that you are about to arrest somebody, you'd say something like "let's 10-16 him." This gives the other officer time to get in place and hopefully the suspect won't understand and have time to react. But if you were to say "Let's arrest him," that might present a problem.
And there are some that are good just to use shorthand and keep those who might hear from immediately recognizing. For example, "11-44--Coroner's Case." If you've got 4 dead bodies, you might say something like "11-44 times four." The casual listener probably won't get that. Its just a lot better than saying, "We've got four dead bodies."
So in my opinion, it would make sense to preserve the codes which are really useful for officer safety and expediency. We should standardize them nationwide and actually make them confidential. That way the crooks wouldn't know what we were talking about. (Yes, they might find out but at least they probably won't be published everywhere) This might mean we would have to change them for everybody. But it would only be a few really important ones.
For codes like "11-14--Dog Bite" or "11-60--Investigate Water Leak", we should definitely use plain English.
Police Academy Student