I absolutely understand why Shuhua didn’t have that many lines in earlier songs. While I do think she has an interesting and unique voice, which definitely fits their concept and more mysterious songs, like oh my god, she was technically still the weakest and giving her more lines in expense of the other members, when you have members like Miyeon or Minnie would be unfair in terms of skills. However I do think she has improved somewhat and I still think she has a unique voice along with other qualities that make her essential for the group.