Oh you wanted "informative and interesting"? Well, as much as I love flying the 22, I have to admit that Robbies are simply the answer to the question, what if you took a homebuilt and made it certified?
As such the Robinson philosophy has always been light weight = more affordable. Add another blade = more weight = more expensive. Not to mention Frank's original vision of people using his design to commute to work,...and you can't park your chopper in between two cars (like the picture they show at the Safety Course) if you have more than two blades.
Besides, they're not going to redesigned the entire helicopter to handle one more blade just for those out there who aren't "comfy" flying with just two blades!
,...just like the rest of the industry isn't going to stop making or using singles just to satisfy the, "never fly anything but a twin" crowd!