I saw that, and I think the "attractiveness" is just another word for a gimmick.
I'm pretty sure in this context "attractiveness" doesn't mean "looks pretty to a viewer," I'm pretty sure it means it was desirable to the engineers.
4 legs would definitely be more efficient than 2 legs, and 6 or 8 probably even better, and possibly a combination of legs and wheels would be the most efficient.
As I understand it, the "efficiency" with >2 legs and/or added wheels is to overcome the instability of a bipedal. When you have a robot that needs to function within the human world, or as they say, a world "designed for bipedals," there is certainly a desirability (or "attractiveness") to a bipedal design.