You get a notification in the notification area when you create files, but not when you create folders. Reproducible: Always Steps to Reproduce: See video
This is because creating a new file is internally simply a "copy from template". Depending on the size of the template, or if the target is on a remote folder, copying could indeed take some time, so a notification might be useful. I am not sure, however, we should add notifications when creating folders, which requires no data copying, so the difference might be intended. Could you please clarify the expected behavior?
In the common case neither would take any significant time but I see your point about how file creation *can* take time. I suppose over a network (or if you have drive issues) folder creation could as well, so I would expect a notification for both.
Also, the notification should not refer to copying, as that is not what the user did (the user doesn't care about internals). As a personal preference I'd like to see the notification if the operation is lengthy (ie if it takes more than 1 second). For normal operation (ie fast) it could still log the notification, but don't distract me with it. For consistency it should behave the same for files and directories.
It seems that this issue has been fixed: now (I use KDE from the master branch of git) I get no notification when I create both files and folders. In my opinion, it's a right behavior. Feel free to comment on this if you think that this bug was closed prematurely.