Not unless you are a professional photographer potentially making money off of that photo. Plus it easy enough to remove water marks that aren't somehow embedded in the photos code. This is just my opinion, to be taken with a grain of salt as I am no photographer.
Actually, the watermark with the copyright symbol simply serves as notice to anybody that the photo is copyrighted and that it is not legal to use it without your permission. Even without the watermark, or if the watermark is removed, the photo is still copyrighted and you can sue if it is used without your writen consent.