Why even call the Sherlock Holmes if it's so radically changed? Just do a new show with new characters.
I've heard people ask the same thing about Moffat's Sherlock
, but it worked pretty well for that.
Christopher Nolan's and Christian Bale's Batman is radically different from William Dozier's and Adam West's Batman, but that doesn't mean they shouldn't have both been called Batman, because there are certain core elements to the character that are shared by both. Sam Raimi's Hercules had very little to do with the ancient Greeks' Herakles, but if they'd given him an unfamiliar name and been unable to draw on the myths (however piecemeal and revisionist their approach was), it wouldn't have had the same resonance. Human creativity has always worked this way, blending familiar ideas with novel approaches, exploring variations on familiar themes.
One could just as easily argue that there are a ton of shows about new characters already, so what would be special about just churning out another one? Blending the characters of Holmes and Watson with a modern and/or American setting is
something new. All creativity is about blending existing elements in new ways, and taking an old story or character and putting it in a new context has always been a common and perfectly valid way of doing that. Creativity is a dialogue with the ideas of the past, a response to them, an expansion upon them -- not an avoidance of them.
Think of it like evolution. Every new species contains most of the DNA of its ancestors, just with a few key changes in content or expression. It's not a wholesale start from scratch, since that would be inefficient and get nowhere in the long run. It's building on the strengths of what came before and adding something new that takes it further. Related species can share a lot of DNA yet be adapted for widely different niches. So why can't a given character like Batman or Hercules or Holmes be allowed to evolve and speciate, to become a whole family of stories branching out in new directions, rather than being stuck in a single fossilized form forever while culture and creativity evolve ever outward around it?