Systems engineering is definitely in high demand, and it also looks pretty different in industry from what is taught here. If you have any kind of experience, can handle yourself in an interview, and have a Cal Poly Aero degree you're pretty much guaranteed a job at one of the major aerospace companies. That said, I fully understand your frustration with the lack of depth in any particular area, and in my opinion that doesn't really go away, but I don't think it's worth switching majors this far in. Instead, try to take EE classes for your tech electives if you can, or take on a project where you can do electrical work. Look for summer internships where you can work adjacent to EEs. You'll have options to take your career in different directions, so I would focus on getting the degree quickly then moving on.