Understandable, but unfortunate. Character art of all 15 EN members drawn by Ina would have been even better than the song.Did you watch Bae's afterparty stream? A large portion of it was her talking about the character designs and how and why she chose the outfits for each person.
And yes I think Ina said she considered doing it and/or was asked to by Bae, but just didn't have time to do all 15 of them, it was too much.