Apparently its part of the uniform. In 2009, a couple of the Justices were wearing them (maybe because the weather was colder?). I was kinda disappointed Scalia was the only one this time around.
I felt bad for the poor Obama girls, they looked pretty bored. I used to hate sitting through formal speeches, mass, funeral, etc. when I was a kid, so younger me sympathizes with their having to sit through so many of these things.
I wouldn’t read too much into that. Kerry, Dole* and McCain were still Senators after they lost, Gore was still VP and Bush I was still Prez, so they were all going to be in DC anyways. Romney is the first President since Dukakis that didn’t have a work-related reason to be in DC, so its hardly surprising that they both happen to be the only recent candidates to not show up for the ceremony.
*did he retire mid-term in '96, or did he just not run for another term that year? Well, he had recently lived in DC, anyways, even if he wasn’t Senator anymore.
Interestingly, the steel barriers are still in place today. The portable toilets are gone, though. The powers that be don’t seem to be in a hurry to take down this fencing stuff, though. I would have thought business owners would push for that.