This piece is referenced by the main.js or the js that loaded the component and so the gulp compilation will probably never have finished and nothing will have changed in your js; or if you deleted assets/*.js you might have no interaction anymore at all due to missing JS files.
Removing any core JS like this - as you found out - most likely will break the application.
As said, the cleanest way for now would be to remove those pieces through an extension. Another solution would be to hide those pieces with Jquery or plain old-fashioned Css.