Because he is the subject, even if it is an otherwise routine work matter, when he is the subject at hand its a life altering matter. Lawyers are a bit like doctors in this sense - its one thing to operate on someone else for the 1000th time, quite another to be operated on.
That said the whole hearing is staged. Please don't believe his yelling anymore than you believe his tears. The guy is putting on an act, as anyone in his position would. I will say I know a more than one scouts clerk and the idea that this guy was crushing kegs and raping chicks while gunning for positions like that seems like a bit of fantasy. Not to say people like that can't get ahead, but its a different sort of aptitude for something as wonky as appellate litigation. If Bad Boy Brett really was the fratstar the democrats claim, it points to the final fusion of what was once an intellectual pursuit, and the dirty and grimy world of politics.
The character being painted of Kav is one of a politician, not a judge. This is perhaps the most troubling thing to me. The spittle and the tears at the hearing are par for the course, clinton also wept.