He was a trojan hourse, and that was all. American retailers would have eventually given way to the consumers demands once word of mouth from Japan got way of saying how great the NES was. Also, the argument of the whole toy thing, if you check some retail stores, they still list video games under toys, some sites have a video game category, but others will still list as a toy, even the impressively built PS3, whic h I find pathetic.
Fact is he wasn't necessary to the consumers, people bought the NES when it came out in the US even without the Deluxe kit that included him. No matter what, the retailers would have eventually wised up and stocked them. R.O.B. just let things go easier and quicker.