Aperture 1.2 @ISO 100 and sunlight anyone?
Assuming Sunny 16, 1.2 and ISO 100 should result in a shutter speed of 1/16000, if my calculations aren't completely off-base. And that's just a rule of thumb, it could be brighter.
Frankly, I think shooting at 1.2 in sunlight without an ND filter is risky anyway. Even with an available shutter speed of 1/8000 you will be bumping up against it constantly, which means no latitude (for underexposure, etc.). Relying on the camera's max shutter speed to cover that scenario for you seems like pretty poor value, if that's the only reason it's necessary and leaving it out would reduce the cost of the camera.
Now using it for other things is a different matter altogether. For example, I don't know what kind of shutter speed you need to freeze a hummingbird's wings (I've never tried). If 1/8000 does it but 1/4000 doesn't, and that's a subject you shoot regularly, then in my book that would be a good reason to stick with a camera that provides 1/8000.