I couldn't agree with you more, Gothick. And it's worth noting that the scene as it appears in the movie is a rewrite that was added on 4/27/70 (more than a month into shooting), and the original version possessed none of the mood of the rewrite. It was a scene that took place in the basement of the Old House with no mention of eternal life and eternal love or appearance of the music box - just Barnabas and Willie arguing, Carolyn arriving and arguing, and Barnabas attacking and demanding Carolyn be taken away. Violence and gore, pure and simple. And considering that that's what's stressed throughout most of the movie, it seems like a miracle that the rewrite was not only added to the script, but that it actually made it into the final cut of the movie.
Here's the capture/quote:
hoDS: Scene #113 - Barnabas: 'I went to her that night and
offered her eternal life, eternal love.'