The scene never made me dislike Sisko; it made him human. Of course he knew beforehand he was going to meet Picard but when you're face to face with the person who was, however much against his own will, still responsible for the death of your beloved wife (in the sense of being the cause of it), you might have trouble keeping your emotions from showing.
Of course the encounter is equally difficult for Picard, as he never committed those actions voluntarily but "remote-controlled" by the Borg. Seeing the human face of the suffering you were forced to cause must be awful.
It seems to me a lot of Federation characters get stick from fans if they ever dare to show that they're angry or conflicted in any way, if they are ever anything other than anodyne ideals. Riker gets stick because he has a quick temper and doesn't suffer fools gladly. Keiko gets stick because she's sometimes stressed out and gets pissed off at her husband. I don't get it. It's what makes the characters something other than cardboard cut-outs.