#1 SmackDown needs a top babyface
As we mentioned, the clear priority is for Becky Lynch to be the top champion and babyface on RAW. The entire 2018 to early 2019 saw the entire RAW Women's division focus around Ronda Rousey, while the SmackDown Live women's division centered around Becky Lynch and Charlotte Flair (and Asuka, to some extent).
Bayley's move to SmackDown was a calculated one and WWE knew exactly what they had with her as a propsect on the blue brand. With Becky Lynch's SmackDown appearances potentially reducing, the blue brand needs to establish a new, fresh top babyface.
Who is a better candidate for that than Bayley? Ember Moon could fit that bill but she doesn't seem to be ready character-wise. If Bayley continues to add an edge to her character, then the sky is the limit for her.