The thing that worries me about Charisma compared to, say, Strength is that it's harder to see what it's doing for you.
If you have a high Strength you can tell because you can haul around more stuff and your punches do more damage, etc.
But if you have a high Charisma, you may get better prices but other than that, how do you KNOW what it's doing for you? If you see dialog options, how do you know you would not have seen those dialog options ~anyway~, with a lower CHA score? Unless it explicitly lists [ CHA ] after a dialog choice or otherwise makes it clear that you would not have had that choice without your high CHA then the only way to tell would be if you had played through with a different-CHA character and happened to remember the difference in dialog options.
Seems like the times I played high-CHA and then low-CHA characters, I did not notice ~much~ difference at all. That may be different in Fallout-4, but then again, they have X amount of information to reveal to you, so they can't ~not~ give you the info you need.... so what would a high CHA really get you? Extra information? LIke, because of your high Charisma, the NPC may say, "You know, you're an okay gal --- I know this other, secret, entrance you can use".... but that's a dialog line the voice actors would have had to record (both player-character VAs and the quest-giver VA) that ~only~ certain characters with high CHA would ever hear. How often could they really do that?
Granted, having CHA "gate" some of the settlement building functions gives it a more tangible effect on the game, but I'm not yet convinced how big a role it will play in actual conversations and dialog.