on my behalf, I would wish to collect more artists from Batch 3 but I haven´t even finished the collections from Batch 1. to me the cards just came out a bit early. I am collecting iKON and Winner and would have wanted to add Oneus and Dean, but man I still haven´t finished Ateez, Stray Kids and Seventeen, with no hope of finishing them as I had tried several times and given up, I´m now collecting Wanna One. A decent band and I´m really sad no one really wants them (but on the other hand ... it makes collecting them easier, so why am I complaining? :D).
if SuJu are added in April/May I will hardly be able to collect them, apart from maybe getting Leeteuk as he is the bias, maybe Heechul, but otherwise there are still previous sets I would have rather finished.
but I do understand what you mean and I actually agree with you, a lot of groups are left alone and I have to question myself "why them" ? I got it with the first batch when the users couldn´t vote, but the second and third .... and if I remember correctly some of the chosen groups didn´t even have that many votes? like Dean for example?