The problem I have is that the main character trait that characters express the most in DS9 (Sisko excepted I guess) is selfishness. Now that's easy to identify with, as most people are selfish almost by default, but I don't find it an appealing trait in a protagonist, which is why I also don't like the JJ Trek characterizations, where Kirk is highly self-centered.
You're definition of "selfish" strikes me as somewhat unique, unevenly applied and unduly restricted to Deep Space Nine. In fairness (and "in my opinion"), Picard was, just as "selfish" as any other character you could point to (at least as you seem wont to define the term). He was also preachy, arrogant and blase at times. Not that I didn't like TNG or the Picard character, but, to be fair, there was a lot to like and dislike there.
In terms of the friction between Sisko and Picard, I have not seen (though perhaps I missed it) anyone mention how uncomfortable and self-conscious Picard got when Cmdr. Sisko mentioned Wolf-359. Picard's reaction gives credibility to Sisko's pain and point-of-view.
Was Picard responsible for his actions as part of the Borg Collective and the consequences? Was Chekov responsible for the death of Mr. Scott's nephew in "Star Trek II: The Wrath of Kahn?"
My personal answer would be "no" to both, however, knowing that intellectually is seperate from the emotional reality of suffering and loss. I think Sisko's anger, resentment and frustration was all very real and reasonable under the circumstance, therefore, I think it would have been a poor choice to have Sisko treat his first face-to-face encounter with Picard as nonchalant and routine.