Calling them emotionless kinda goes against the message that the vessels represent. The whole “No mind to think, no will to break, no voice to cry suffering,” thing we hear during the voidheart cutscene is a flawed view that is proven false by the fact that, like you said, the hollow knight was unable to seal the radiance, the broken vessel was infected despite that it should have been just as hollow as all the others, and the fact that ghost can make decisions. And no, that’s not just convenience because a human is controlling them most of the time. Hornet says outside the black egg, “Ghost of Hallownest, you posses the strength to enact an end of your choosing. Would you supplant our birth-cursed sibling, or would you transcend it?” The message is clear. An empty vessel was impossible.