Re: Why did they bother...
I watch two different TV shows about Sherlock Holmes and Dr. Watson. Different actors, different settings, different portrayals, even different sexes for some characters. I don't want to watch, say, Jonny Lee Miller doing a Benedict Cumberbatch impression. Liking both doesn't make me any less a fan of Sherlock Holmes stories.
"STAR TREK is... Action - Adventure - Science Fiction."
-- Gene Roddenberry, 1964, top of the first page of his original pitch and outline for Star Trek