You have pointed to the exceptions to the rule. Yeah, sure it CAN make pretty good bonsai, but you also run into a nice serissa every now and then
. What you haven't shown are the hundreds of failed, awkward, ugly and plain worthless ERC stock and "bonsai" that are out there.
This species typically makes pitiful bonsai (regardless of trunk shape). As Dorothy pointed out, it has some quirky growing habits that work against bonsai treatment. Growth is mostly rank and lanky. Juvenile growth is prickly, unmanageable and only gets worse. It also seems to prefer to push mature growth from a few established growth centers on specific places on a few branches. Those centers take a while to establish and never show up where they're needed in a design.
Sorry, this species ain't worth the trouble, unless you find an exceptional AND collectible trunk--if you're that lucky, you have probably already won the MegaMillions jackpot and can afford vastly superior Japanese imports...
I lived in the Blue Ridge Mts. for some time. The huge majority of ERC there are also mostly beanpole, vanilla crap. Those crappy ERC grow alongside very nice and sometimes spectacular native common juniper, table mt. pine, white oak, beech and Virginia pine.