Currently ONOS UI has some features like install / un-install / activate / deactivate ONOS apps.
Similarly, ONOS UI has a feature to add intents by selecting either hosts / end-point links and then create a new intent. There is also a feature to view / list available intents. However there is no way for the user to remove a selected intent via GUI. Hence for this purpose, user has to go back to CLI mode.
Adding "remove-intent" via GUI, would make ONOS UI self-sufficient to do certain mundane tasks, thereby reducing a dependency on CLI.