What if solar sails was actually a fabric of hundreds of tiny modules, that each could both collect energy from radiation (starlight) and provide thrust in a single direction?
That would make it not-insane to construct spaceships that looked like marine ships with old-school sails.
@zatnosk I'm pretty sure that's been used in anime before, not that they need an excuse to have spaceships that look like seagoing ships.
The amount of starlight hitting a spacecraft in interstellar space is not sufficient to provide an appreciable amount of thrust. I suspect sails would end up creating more drag in the interstellar medium than the thrust they could provide from starlight.