diversity to cover all one's bases and obviously this is with hindsight...
this is more an economic and business decision
Lisa - covers your rap/dance and SEA demographics
Sana - covers your Japanese demographics
Jennie - covers your SK and English needs
Seulgi - covers your dance/vocals and your korean demographics
Tzuyu - covers your Chinese (yes I know she's taiwanese) demographics and visual
Nayeon - covers your SK demographics
Irene - covers your oldest and visuals