"Dull" feels like an awfully harsh word for a wonderful actress who was (then) in her 80's. I saw the show well into its run and thought she was delightful. They obviously wanted an actress who might evoke the qualities that Etienne Girardot had in the original 1934 film (when the role was that of a male proseletyzer).
Mary-Louise is a wry comic actress and Worley, Martin and Imogene Coca are clowns. When I saw it, Wilson was very funny but didn't dominate the show the way I could imagine Worley in particular doing. I loved the revival and am always glad to have caught Mary-Louise in another show to go along with Full Gallop, Grey Gardens and her beautiful performance in 4000 Miles at LCT. Lovely actor!