Price is only dictated by what people are willing to pay for one's product. This is not to say that the ROO's are justifiably overpriced though.
Concerning the movement, what is stated in that article is that the writer refers to AP's use of another manufacture's movement in their watch. What the writer doesn't note, though is that the movement is also used in other high-end watches as well (JLC 889, anyone? Have you seen it in a "run of the mill" watch?)
Please note that AP uses a solid gold rotor weight and they are eccentric in their movement finishing. I am surprised that they don't put display backs on ALL their ROO models.
The base movement is simply driving the "motors". Consider the module the "complicated" part of the watch. That is also beautifully finished and does not provide a "jerk" when starting the chronograph, as I have seen in most modular chronographs.
Finally, please consider the fit tolerances of how the parts come together and the finishing of not only the exterior of the watch, but inside the lugholes, the screws, and between laser-cut and engraved parts. If you have the chance to inspect a gen ROO, I recommend taking a loupe with you. I think you'll see that AP was not sloppy in executing the quality of this watch.