Frankly, I think it is because they don't really want their customers to know how simplistic they are. They are happy having customers thinking some magical sensor is monitoring every characteristic of the oil and essentially doing an oil analysis realtime.

I bet most people would be rather disappointed if they really knew how they worked, e.g., look at the new brake pad serivce life estimators. I'll bet that's a real simplistic system. It will be interesting when enough miles are on the vehicles to see some reports on what the "projected miles to change of pads" says just prior to the hardwired brake sensor lighting-up.