I'd love to try to negotiate with raiders
Indeed. When you check Reilly's Rangers computer, their mission reports say they often get altercations with the Talon Company where they insult each other without drawing weapons (Except for one time)
While in the game, every Raider and Talon Company Merc are crazy, bloodthirsty people reduced to the humanity of a tiger infected with rage. How do the Talon Company get their members? They are an organization, people must be able to sign up, in exchange for a bad deed to perform I suppose. I doubt the Mercs breed their members. Same thing with Raiders. Beth designed the Fallout 3's raiders to be animals, while there could have been interesting discussions and negociations with them. But instead they are uni-dimensional and serve only to provide experience points and loot.