Mike,
I like the extra animation and character that you can paint into a bust of someone yelling. I've done several busts over the years and most of them have a rather passive, almost blank expression that doesn't reveal much of the character or personality of the subject.
I don't think these busts are lacking anything by not having arms - if anything the lack of arms forces the painter to focus more intently on the eyes and the facial features to convey the true character of the person being depicted.
Cheers