I think a lot of who Hancock is and what Hancock does goes under the radar, particularly his grand accomplishment with Goodneighbor: if you look across the entire scope of the Commonwealth, you’ll notice there are no ghoul residents in the vanilla settlements (with only one notable exception), and the only main groups who have ghouls are the Triggermen and the raider gangs. Ghouls are ostracized, and bigots exist in every main faction. However, Hancock did something rather remarkable, and he established post-Vic Goodneighbor as a place where ghouls could live alongside non-ghouls, and it’s the only vanilla settlement where you see this. Considering that Diamond City elected a man who ran on a platform of bigotry - his “Mankind for McDonough” platform clearly dehumanizing the ghouls of Diamond City, some of whom might have even been part of the creation of the settlement - Hancock did the opposite of his “brother” and he overthrew a monstrous tyrant to establish a place where ghouls would never be afraid of being tossed out or dehumanized by the governing leader.
The Brotherhood of Steel, the Railroad, the Commonwealth Minutemen, and the Institute can’t lay such a claim - only Hancock can. And yet, Hancock seldom gets any recognition for this. It’s such an important and monumental feat, and I hardly see anyone applaud Hancock for this.
Hancock is clearly a man grappling with a lot of trauma - despite being the only person to try and help the ghouls of Diamond City (as no other person or group seemed to try and intervene on behalf of these people), who were thrown out by the city, he’s clearly haunted by all the lives he couldn’t save, and the people who died. Hancock was so filled with disgust at who he was - a man who didn’t protect an innocent bystander out of shock and fear - that he would rather take a concoction that could have killed him just so he wouldn’t have to look at himself in the mirror and see that man anymore. He has dialogue about how people don’t want to talk to ghouls - mentioning it’s rare the protagonist is in his company because it’s rare, and how ghouls turn to books because they often don’t have anyone. Being a ghoul is clearly something that leads to some level of isolation for him, particularly when he leaves Goodneighbor to go on one of his sabbaticals. Hancock is someone who is in pain, and his friendship with the protagonist can help alleviate that.