I don't think the lack of anchorhead scene makes the Biggs scene pointless. I think not having the Biggs scene at all makes his Death scene pointless. It's hard enough for the audience to remember that Luke Mentioned Biggs at the dinner table when his only scenes in the film are during the dogfight. I felt the Biggs scene finally added weight and depth to what had always struck me as a "huh?" scene. Biggs dies, like every other rebel pilot died, but for some reason, we're suppose to believe that specific death affected Luke? He gets a mounrful musical cue? Made no sense. As a hard core star wars fan, of course, I knew the history between the characters. Back when I was a kid, watching the movie on our old, enormous VHS deck, Biggs was just some guy, and his death held no more meaning than the scores of others that had preceeded it. I've seen parts of the Anchorhead sequence, I understand why it was cut, it's not terribly good. The Biggs scene on Yavin is good, and gives us all the background we need to drive home to the audience that A) this is Luke's best friend from back home, and B)His death during the battle could potentially make Luke lose it emotionally, and therefore carries a lot more signifigance than random rebel pilot death.

That's just my take on it