I think that what you're trying to describe is actually two specific problems that the game has after meeting up with benny.
First and foremost, the game straight up info dumps practically every bit of information you could ever want to know with regards to the why, how, and what of the story as soon as you get the chip. There is no development or additional mystery aside from a few questions about how dickish the various factions are (which were pretty much already touched on before. Why was vegas spared from hellish nuclear war? Why was the chip important? Who is Mr house? What was benny planning? The games fucking up and tells you. Unlike the original fallout, which forces you to find out more about the super mutants before you can deal with them. Even worse, once you decide to side with a faction, there is no question of what the factions want you to do (battle for the dam). No, it becomes basically becomes one long unvaried checklist.
Which brings me to the next problem: The game takes away most of your sense of self direction as soon as you deal with Benny. I don't mean that it takes away the ability of the player to decide where to go or what to do. Rather, in the beginning of the game it gives you the vague singular goal of "find the guy that tried to kill you and recover the package that you lost" which was a goal that made sense for you, the player. Right after you deal with benny, everyone and their dog suddenly comes to you because you can apparently do all sorts of awesome shit. The only problem is that it ends up being a more or less identical progression of other people (even a robot that is only supposed to take orders) telling the player to either deal with or kill various factions, most of whom are the same. The game makes a big deal about picking which of the factions you want to have in power the most, but it is largely disconnected from your actions on the given quest lines. After all, it's a hell of a lot more difficult to root discussions of tyranny and society in a game about shooting people in the face (or occasionally talking to them) than it is to have a story about "go kill that douche bag."
Id est, with benny, the game tells you why you are in the given situation and then lets you do whatever you feel like doing about it. After benny, the game tells you what to do, then offers justification for it. It's more complicated than that, and qualifiers obviously abound, but that's what I'd boil my critique down to.
