The issue isn't "The violence", it is the way the violence plays out. It's impossible to sympathize with Booker's sorrow and regret over what he did at Wounded knee, when you are literally feeding live people to ravens and setting them on fire until they are piles of ashes. ALL THE TIME
You can't empathize when you are between real human emotions and cartoonish levels of inhuman brutality goes on.
Heck, there is even a time when the old general ask you to kill his soldiers, so they can die a good death. I doubt he had in mind that I have burning ravens eat their eyes.
While i see your point i disagree that Bioshock infinite shouldn't have had vigor's i do like many of the points you made. From what i've heard the Vigors were meant to be stronger and were some how going to be linked to Elizabeth. You could tell from the 10min game play trailer released at E3 her powers were not so much about pulling things from other realities as it was more like she had a great deal of plasmids at her command.
You know, this reminds me of Egoraptor's second Castlevania Sequelitis episode... though I personally thing his Sequelitis videos are bogus now that I've seen his actual skills at gaming and how they fail in the light of what he said gamers would do in these videos, but that's aside the point. the point is, in this video:
The vigors were a big problem to bioshock infinite but it wasn't that they were there that made the game worse, it was the fact that they were all extremely weak compared to their counterparts in bioshocks one and two. The decision to give the player such weak powers and on top of that giving them a limited list with customization was where they went wrong.