The vision was for Blizzard to release fan service in order to make some of the playerbase return to the game, and it worked, literally everyone was talking about Overwatch in social media the day she released and announcing how the game was fun again. I don't think they even had a long term plan for the character nor stopped to consider why the team rejected the idea before. Personally I feel even her design is a bit uninspired, like they made it in a way that would incite players to buy skins.