What you gain by a manned mission is they can react to interesting areas on the asteroid's surface. They could go here, there, there. And they wouldn't have to rely on remote navigation.

而载人任务的好处是他们（宇航员）可以对小行星表面感兴趣的地方作出反应。他们可以去这儿，那儿，那儿，而且他们不必依靠远程导航。