A stationary multihit move will never be an offensive tool when it's negative enough to be punishable on block. Jade has a lot of the same; b1, b2, f2, they are all the same "has range and shit frame data" moves that would be amazing in a game that doesn't have moves like liu's f4, jax's f3 and f4, baraka's f44, jacqui's shit, anything Kabal does, and on goes the list of better, single, multipurpose moves that provide with options including high combo damage and get more done than all of Jade's kit together.A lot of the advancing mids put the character using them in some sort of danger because there moving along with their hurtbox, jade's hurtbox is the same and her hitbox for her back 2 extends a lot to catch anyone using their forward advancing string. back 2 isn't meant as a forward advancing mid like other characters who have them like baraka or kabal. Its mostly meant to be defensive and reactionary, to whiff punish. Changing this defensive tool to an offensive one as well isn't a good idea as long as balancing is involved.
You can of course look at this individual move and be optimistic about it but if you look at Jade's buttons in a situation where you have Jacqui or Baraka in the neutral, whiffing or getting ducked / backstepped / jumped over on any of her "otherwise amazing" moves will cost you more hp than it will cost them if they guess wrong and get hit even by a f21 combo.