if i were a betting man i would gamble that they were probably used for there sonic performance. that said jerry is seen with only 2 clips on one speaker and i have seen one of his cabs with the generic black plastic clips also. i would have to dig to find the photo, but it's out there.
NICE CLIPS JEFF!!
i got lucky! my uncle is a machinist and once i threw him the layout of the clips he had them to me in a week. free of charge. they look exactly like yours. not to stir the pot, but the new hardtruckers have never had them right!
the real genius of the clip is the hex screw. parish is seen using a drill with a hex key onstage removing a speaker. it doesn't slip or strip like a phillips screw might. when jerry blew a speaker the job was to get in and out, without any damage.
one last note concerning the clip is it's height. your standard speaker would need spacers to accomodate it's surrounds height. JBL's are beefy speakers all around and the clips are pretty much made for them.