Yast modules will no longer open if you delete var/log/YaST2, if you delete the journal folder, it will remain empty and you can’t get any messages from it. Other folders like zypp, cups and audit will be recreated. If you are annoyed by the logs you can edit the behaviour in /etc, but only do it if you know what you do. Imho it is not worth it to play around with that, the potential issues you can create are more problematic than some log files.