Don't get me wrong. If someone wants to do a serious, historical Arthurian epic set in post-Roman Britain, more power to them. I have fond memories of David Drake's THE DRAGON LORD, not to mention Parke Godwin's Arthurian novels.
Parke Godwin's novels are fun, but they're not "historically accurate." As
Bob the Skutter said, no such thing is possible - Arthur didn't exist in anything like the form we have him from any period. No real records from the time. Zip. Zilch. Nada.
The "real" Arthur is the obne found in literature from the 12th-15th centuries, just as the only "real" Sherlock Holmes is found in a series of texts by Doyle.
But the Arthurian legends are flexible enough to all sorts of approaches--from Broadway musicals to R-rated blood and thunder. And, traditionally, most of them take place in some sort of vaguely medieval age of chivalry anyway.
But they're no infinitely flexible. My example, which you borrowed above, was
Hercules and
Xena. There were always core elements there which made those shows a version of Greek myth.
I thought, after the first episodes of
Merlin, that the depiction of Merlin himself moved too far away from a core element (for me it has little or nothing to do with unverifiable historical accuracy). It was more akin to watching a movie about Sherlick Holmes in which Holmes is a male prostitute played by Keanu Reeves. At a certain point, it becomes something other than a Sherlock Holmes story.
MERLIN is a teen-friendly version with cool monsters and magic. It's HARRY POTTER meets SMALLVILLE meets CAMELOT.
Works for me.
Well, enough smart people here (including yourself) say it's worth viewing, so I'll pick it up on DVD. I need it for the thousand-plus Arthuriana collection anyways ...
Of course, it still looks to me like Meg Cabot's modern-day high school Arthurian reincarnation story,
Avalon High, is a better kick at a Buffy version of Arthur's story. But I'll look forward to comparing them.