reaction to the Merlin episode Excalibur, no spoiler

I'm all for reenvisions of the legends to suit the contemporary pop culture trends. It's the same thing Chretien, Tennyson and Bradley have done. I'm enjoying the new tv series even though it is Smallville A.D. 500. So why, of all the irrational things, does it bother me that, when they drop genuine names from the legends will-nilly with no regard for their characters' traditional stories, they couldn't trouble to give Merlin's mentor the name he has in the sources instead of pulling one out of their butts?