But isn't part of the point of DNI of any stripe that it many of the things a normal pilot would glean from looking out the window are piped directly into the pilot's brain?
Not necessarily. The system descriptions don't imply this actually happens, only that DNI systems allow fluid control over vehicles.
As far as i can figure and recall things, normal neurohelmet merely transmits balance, whereas DNI systems add kinesthetic sense (that is, ability to tell where and how your body is positioned, in this case body being a 'Mech) and replace part of controls with thought. Machina Domini extends this concept even more.
The Clan EI system might actually include visual information, this would fit the name, the fact standard ProtoMechs don't really allow the pilot to even look at screens, and that it adds ability to make aimed shots and other sensor information.
Then again, IS ProtoMech controls are based on standard VDNI, so it might allow visual information. Then again, given that system's requirements, it is possible the pilot uses some kind of conventional VR display (with no relation to the VRPP system) with VDNI.
That said, i do think torso cockpit differences don't seem large enough to make it distinct from small cockpit for bVDNI rules. Not to mention art depicting torso-mounted cockpits nearly always with what appear to be windows or viewports...