The Kunitz - Malkin - Neal line was together for 3 games (combing game 1 of round 1 which Neal got hurt in second, and game 1 of this round where they played together for the first 2 periods). In that time, they had all of 2 even strength goals, one of which was the terribly weak Douglas Murray goal in the game 5 you speak of.
The Iggy - Malkin - Neal line/Neal - Malkin - Iggy line actually has just as much even strength production. And while you can be quick to point out that Numbers don't mean anything, they've also looked very good over the past few games despite not scoring, and I don't buy the whole Malkin is looking good in spite of his linemates. I've seen Iginla and Neal play very well and strong down low, getting the puck deep and retrieving (something many seem to think only Kunitz can do for Geno).
That's not to say that the lines may not be better the other way, but just pointing it out that It may not be sacrilege to suggest that Bylsma, the guy with an actual vested interest I. The outcome and who gets to evaluate the lines up close during both games and practice, along with the players themselves may actually know what they are doing. Oh, and that there may just be a tiny bit of confirmation bias going on this forum that has convinced itself so assuredly that the Neal - Malkin - Iggy line is the worst possible line that could ever be constructed.