As for the 18-21 activities, I agree there need to be more. I went to the first college club meeting on my last cruise and walked out when the CM who was running it told us which bartender wouldn't card us. They really need to figure out better ways for the young people who can't/don't drink to have fun.
Did any 18-21 year olds actually try to get a drink from this bartender? Although I believe your statement, I highly doubt that anyone would risk their jobs or their friend's jobs, maybe they were kidding? Plus, wouldn't the parents see the charge on the card and question it? I sure would!
I have a DD who is 12, would I allow her in the stack even though she has an older brother and hangs out with him sometimes? No, but not because I'm afraid she'll see something she shouldn't but because I know she will be BORED up there. When they "Invaded aloft" on the Wonder she didn't like it becasue everyone hogged the video games and there were no activities to speak of... I guess the activity WAS to be allowed to hang out up there.