The original ending tested poorly with screening audiences. They liked Audrey and Seymour so much that to have them be killed and eaten by the plant was too much of a "downer." It completely fizzled and took the rest of the film with it. What had worked on stage didn't work on film. So they chucked the expensive finale.
The creative team actually went back tor work to reshoot the new ending, after production had wrapped... and it wasn't cheap to call the actors back and build the sets. And, in fact, one of the trio girls (Tisha Campbell) wasn't available to do the reshoot, so they used a double from the waist down. If you watch their last "new" shot, where Seymour carries Audrey in a wedding dress over the threshold of their "dream home," the three girls are dressed as bridesmaids, and they walk by the front of the camera as it pans down to the little Audrey III plant. You don't see Tisha's face in the shot, because it isn't her.
"Jaws is the Citizen Kane of movies."
blocked: logan2, Diamonds3, Hamilton22