Trying not to start a "what is Art" thread... ;-)

Sweeping generalizations all and your mileage will vary :

I'm going to say "mostly no."
These things are primarily defined by their utility and not their
adornment properties. "What about a nice hair comb?" The utility is
part of adornment.

Pop psych would tell us that they are worn for status display and so
is jewelry. But I think there may be a niggle there : just because two
things are used for the same purpose does not mean they are the same
thing. Necessary and sufficient. Status display is neither necessary
nor sufficient to declare something jewelry.

People want them to look good, chose them based on ideas of design.
But that's "I'm going to wear this, I want it to look cool" rather
than "I want to wear this because it looks cool."

I'd say that they are ripe for treatment as jewelry, for better
integration as adornment items. At this writing, aren't most of these
electronic peripherals designed to be cool/attractive/designy in their
own right as stand alone items? Even an earhook phone has "cool pod"
and "ergonomic hook" and we really think of the item sitting pristine
in the case at Best Buy. Somebody will walk up and say "cool ear slug"
but won't say "that ear slug looks so good on you". That gap is ripe
for exploitation and improvement. No doubt there are people that have
been working on this and related ideas for some time experimentally.
The wearable computer people come to mind.

Doh... there's a well established long history of this exact issue.
It's called "the watch".