Hi Peter,
In Konect Manager we try to keep it simple, so we offer the most used set of permissions. We tend to find users that create a record often need to reopen them again at some stage, which would be in edit mode. The create only option would lock users out of editing the record they just created, the only work around would be to create it again, so your administrators would need to deal with double records.

If you have a requirement to prevent users from editing a set of existing data but still create on this dataset, create a form variant and a query that matches the records these user can freely create and edit.

Michael