User blog comment:AK151/So... Episode 9 (and some blind speculation)/@comment-11188061-20130913055908

And before I forget, well, Ruby is the youngest out of all of them. More importantly, she's the one with the least sense of responsibility - if everything up till now hasn't convinced you of that fact - and was literally the embodiment of playfulness. It didn't feel weird at all would act like a clown during class because of plain ol' boredom.

It's likely Ruby doesn't understand what it means to be a leader, and does not feel like anything has changed at all. Basically every reasoning you've given there never even entered her head until someone (likely Weiss) points them out to her face.

Blake would at least smile in response, or chuckle lightly. To Yang and her it's like watching a little sister fooling around a bit. To Weiss however, it's watching an equal (or someone lower) being made her leader, and that leader now is smearing all kinds of mud on their team's reputation and pride.

You know what Ruby would say to Weiss? "Don't be so serious, geez!"

And for some people, that remark would be completely justified. LOL.