I don't think there is any reason they can't box, but I just don't like it. Where some of them may lack the skills, they sure do have heart and have put a lot more into their fights than some of the fights between guys.
But for me personally I don't like seeing women punch each other in the face. I don't want to come across as sexist but there are differences between men and women. Each has its own strengths and weaknesses. I did some mixed group training once and a girl was holding up the focus mits. Unfortunately she wasn't holding them properly and when I jabbed one (lightly!!) it kicked back and hit her in the face. I felt like sh*t for the whole weekend. Almost as bad as when a girl was sparring with me and sprained he wrist while hitting me when I covered up. Definetly a loose-loose situation.