The sneak preview of Apocalypse Now that I saw (in suburban Atlanta, at Perimeter Mall) had Coppola in attendance. He was tired and looked rather concerned, and had to put up with a lecture afterwards from god-knows-who to the effect of "it's too long, you've got to take stuff out." I countered with "no, no, you've got to put more back in," upon which he wearily replied that there was the whole sequence with Christian Marquand but there didn't seem to be the time to fit it in.
Remember, at the time of the preview he had been working on the film for years and everybody was scared that it would turn out to be a complete bust. Distributors, then as now, hated films much over two hours. I suspect Coppola really wanted a longer film.
Everybody knew the film without the plantation sequence. To me, having had that tantalizing glimpse of it early on, gave a different sense of expectations for the film. Somehow that pause, having the men venturing almost to the edge of the stone age and then finding a pocket of people living a perilous colonial existence despite the war was just another of the absurd contradictions of the modern and the primitive that made the movie so endlessly fascinating. It did bring the forward drive of the movie to a halt, but so did the Playboy bunnies scene that made it to the final cut. Ultimately, though, I had hoped for more in it than a dinner and a bedroom scene.