I won't speak for female readers, but I will say it frustrates me when the female version of a male superhero is nothing more than the distaff counterpart - "Hey, let's make this guy, but a chick." So I for one appreciate when the character is, "Hey, let's make this guy, but different in a lot of ways, sex being only one of them."
A fully realized evil Banner without the Hulk's power would be a threat. The Hulk, with or without evil Banner, was enough of a threat that the world's greatest geniuses literally created a plan to launch him into space. Go read the Planet Hulk storyline. And then read World War Hulk, because the Jolly Green Giant was not a fan.
Point is, both Banner and Hulk are legitimate threats to take seriously. The irony is that each one effectively limits how dangerous the other can be. The scary part is when they get along.