A lot of these ships are from before my time, when fans had visions of these huge single stage interplanetary rockets powered by atomic motors. As I little kid in the '60s I caught the tail end of the sensibility.
It's somewhat ironic that a real starship traveling at a significant percentage of light, maybe even 90% or better, would likely have a shape reminiscent of those classic rocketships, to better pierce the interstellar medium (which isn't a true vacuum) and assuming it was made of truly advanced materials.
It's been argued that maybe science fiction has been too successful and popular. The reality seen on the nightly news can't match the excitement of the cinematic visions played out for what has become a rather cynical audience overall. I hope that's not true, that we still have souls dreaming and aspiring to go "where no man has gone before." That aspiration got us into the air and onward to the Moon. I hope it can be regained someday.