I agree that the singers should not take themselves too seriously. Those that do are at best making themselves look foolish, and at worst are a bore.
However, have you ever heard the saying “for a ha’pth of tar the ship was spoilt”? In my view, it is the booker’s job to hire appropriate entertainers for his clientele, and it is the Karaoke Presenter’s job to take such steps as to ensure that his patrons have fun, by being adequately and properly prepared. Both jobs require talent and skill. If either fails through indifference, sloppy management or arrogance the patronage will suffer badly, I’ve seen it happen. For those of us who only have one evening out a week, we don’t want it ruined by selfish, loud-mouthed louts or by sloppy presentation. I was merely pointing out what my friends, my husband and I look for; others may choose lower standards if they wish.
Best wishes