You make an interesting point. I think there are many people at law school that feel the need to throw around their accomplishments, probably for the sake of feeling like they're better than other people. What they don't realize is that this annoys everyone, including those people who may have higher GPAs than them anyway, but feel it inappropriate to be so arrogant as to bring their attention to it.
Arrogance is not just a big taboo in law school, but also in life in general. No one likes a cocky person. If you can't be happy about your achievements without telling everyone around you, including people who are not your friends and don't even go to law school yet, then you need a serious lesson in self-fulfillment. You shouldn't need to make yourself feel smarter than others to avoid being miserable.
For what it's worth, I've never before heard the term "Rising 2L." Everyone at the school now refers to incoming 2Ls as "2Ls" only. Considering that TopTenPercentum felt the need to brag about his/her class rank right off the bat, I got the distinct impression that he/she meant something different by the term. But I digress.
For all of you incoming 1Ls out there, don't be disillusioned by cocky people. There are many more of us in law school that can go about our studies without being on a mission to make everyone else feel inferior. And, as in the "outside world," those who are arrogant quickly find themselves without much company, except for others just as arrogant. Talk about misery.
In an attempt to avoid making this entire Law Preview discussion about how annoying arrogant people are, I will end by saying that humility is a virtue. It's silly to recommend that everyone be arrogant; I sincerely hope that no one takes such advice, regardless of whether it makes certain people feel "more comfortable." Considering the feelings of others is an important skill to have, regardless of your disappointment that you can't boast about your brilliance at every opportunity.