as with anything, the substance is more about what you do than what you're called. of course, sometimes the pay can be more about what you're called than what you do, but that's another story.
i suppose a vascular surgeon doing carotid endarterectomies, a neurosurgeon or radiologist doing endovascular coiling of intracranial aneurysms, or a neurologist involved in deep brain stimulation (though that's more likely a neurosurgeon) could all say they're doing "interventional neurology." the term strikes me more as marketing than anything new. what most folks seem to be talking about is neurologists getting in on the money that comes with doing endovascular procedures.
i don't think it has caught on in the general population of neurologists though. even though more neurologists seem to be gung-ho about possibilities for new treatments coming up and some are hardcore intensivists, most neuro folks just aren't really rotorooter types. the overall culture of neurology just isn't very mechanical or procedural like cardiology or GI. not to say there's anything wrong with that.
as far as the name game goes, with interventional neurology, i think of it like biochemistry, biophysics, molecular biology, molecular genetics, biomolecular engineering, etc...it's just a name stamped on a very broad idea. whatever the title, as ray charles said (in the movie at least) - "it gon' do what it do, baby!"
i don't see anything wrong with neurology taking on more procedures, but i think if you really want to fix carotids, be a vascular surgeon; if you want to clip or coil aneuryms, do neurosurg, etc. etc.