Who knows? What were the terms of the licence? Did relations between the firms break down at a certain point? Did Bioware have an old agreement to produce up to N games using D&D stats and KoTOR was the last one, but WotC didn't want to let others of their trademarks be used with it, or Bioware didn't want to promote WotC's trademarks?Why would they not have publicised Star Wars D20 in the marketing, had they used the licence?
I don't see any reason to suppose that this would all be public. But given that BiowWare clearly had a licence for Baldur's Gate and Neverwinter, it strikes me as unlikely that their use of a similar framework for a later game happened completely independently of that framework.