I was watching 2nd,3rd and 4th gen idol performance and I noticed in 3rd to 4th gen it slowly transition not in style but idol talent in dance and vocals. I think in gen2 to gen3 (not including gen3.5) you can notice who is the main dancer and who is not more than 4th gen. imo not every member need to be great vocalist or great dancer a group balance each other and it work. However, watching 3.5-4gen idols videos made me notice something "average vocals" it just made me think "which member is a singer and which is an idol" ,"who can sing an emotional ballad, who will sing with emotions and completely pull the audience?", "which idol can be a musical actor?". Idols used to want to prove that they're more, and break their idol image. I think it's because now not a lot care
This is just after watching videos I'm sure that there are a lot of talented vocalist idol and maybe they still didn't get the chance to shine (my opinion is only based on what I watched , it might change)