The main issue is not being able to say or do stupid stuff, because you can do that. That main issue is that it has absolutely.no.consequences.whatsoever. I could slaughter entire factions, I could commit a GENOCIDE and still march in to Diamond city where people would greet me with same repetitive monologs about "bad weather and sore feet" (figuratively speaking). I could throw around naked corpses and cut them in to bloody bits and pieces and the passing by NPC's would only greet me with a "hello..?" .. I have a freedom to do nearly anything, be as cruel as a man can be, and no one in the game cares two bits about it. That's my biggest problem. I want to have to face the consequences for playing the character I wanna play, I want to have my character be hated, feared, despised, envied, adored, loved.. Have the choices I make in the game actually affect on how my character is perceived.
It's called having to take responsibility for your actions, a thing maybe only us "the more mature crowd of gamers" can understand.
You know there used to be games where you could actually deny yourself the possibility to ever finnish the game if you [censored] up badly enough.... Stuff like that really made you pay attention and take regard in to your own actions, instead of just skipping dialog and cinematics to streamline through the story to reach the taken-for-granted ending. Those games we used to called RPG games, linear games were either platformers or shooters or something else.