I have nothing against Watson being a woman, couldn't care to be honest. But is it actually necessary to do a modern-day take on Sherlock Holmes for American audiences? We already have Sherlock, and that's readily available on DVD for Americans who are interested.
Yeah, I know this is quite common, and in some cases the American version is just as popular as the British original, such as The Office or Being Human. And indeed, there are even American shows which are similarly adapted for the UK, like Law & Order. I just don't see the necessity of it. American and British culture isn't that different, do people really only understand a show if everyone is driving on what they consider the right side of the street and if they speak with familiar accents?