may be because the ability to sing will make one idol survive in this industry.. idk

but in oder to be an idol you must be able to dance too

that's why they are in a group, not a solo act like BoA

After all....
why are you being a singer? For dancing? I don't think so

what about both? keke ><

I think it'd be better to be a great singer and okay dancer

Here is how I see it

Taeyeon-best potential to be a singer, but her idol status may not be there since she can't dance all that well

Hyoyeon-I am sure she could be an idol but her main attraction is her dance but its not like her voice is terrible

well dancers may give a better performance but singers sell albums so which is more important for kpop groups

that is why they are called singers

Their K-pop idols they should be able to sing especially if you're a solo but if you're in a group it still helps to be able to sing

judging from K-Pop Star Hunt