Well that’s not exactly correct. You can yaw and pitch while in cockpit view. In the settings under the camera section you need to turn on “home cockpit mode”. With that enabled then yaw and pitch work. Unfortunately when enabled, you can’t click anything with the mouse so it essentially makes having yaw and pitch ability useless. You can’t fly the plane without mouse control.
What I normally do is setup some custom camera positions with my different orientations. For example, I’ll use the home cockpit mode trick to turn myself around. Then I disable home cockpit mode and then save that camera position. You have to disable it first otherwise you can’t save the camera position. Then whenever I want to turn around I just recall the saved camera position instead of using yaw/pitch. I do the same for looking left and right. With these saved I can then translate around the cockpit in whatever orientation I want. It’s a work-around at least.