Rick Berman is notorious for being a misogynist. He made various “sex appeal” decisions throughout Trek for the sake of viewership (adding 7 of 9 to Voyager, swapping Jadzia for Ezri on DS9, making T’Pol wear skin-tight clothes + the decon chamber + her Pon Farr phase)
Odds are he didn’t think Ms Bujold had the right “look” for the role or something similar.