I think Kidd and a few of the others should have had more of a direct role in the pre Yonko saga(Kidd vs Luffy at the start of the timeskip would have been a good idea, for example, and they probably should have had more going for them in Wano and it's war,as opposed to the samurai), but it's not particularly horrible how they were implemented. All of them having Law's focus/backstory wouldn't really be needed nor would it really help the story I don't think