Couldn't the same be said of any era name? You wouldn't rename the "Warring States Period" because Europe was actually fairly peaceful at that time.
I guess "The Dark Ages" evoked a more universal idea that there was no progress anywhere while the "Warring States" period is understood to be more local.
But personally, I was bringing to light arguments I've heard against calling it the Dark Ages.
Don't have a personal axe to grind either way.