Developers set a constraint in Dolphin that deny Dolphin to run with root permissions. Hence, if you want to perform an action that require root permissions, such as rename a file in /etc/ folder, you are forced to use terminal or switch to another file manager.
On recent versions of GNOME, you can click the Files entry in the panel to access the a specific location (remote or local), connect to a certain server (FTP, SFTP, SAMBA, etc.), access your bookmarks, open a new window, as well as to change its default functionality.
The eOS team puts in a lot of effort refining the UI in all of their apps. You will definitely notice the nice touches here. For instance, contrast levels are clear enough to read but not overdone to give "pop" which takes away from usability.