First off, I'd be interested to know why being white and from a western culture should disqualify them from being able to compile a list of sports and rank them by using a methodology of their choosing (flawed though it may be). I object to your insinuation that race and culture effect the quality of the list.
ESPN is an american company if im not mistaken, and badminton is not as popular over here in north america than in asia, thus leading towards the bias of popular american sports as difficult
Interesting how they can group martial arts as one big group but have 4 different groups for skiing (5 with water skiing... ) Fishing isn't physically demanding (maybe deep sea fishing as an exception) but it still is a difficult sport. The whole "difficulty" thing is kind of ambiguous to begin with... There are lots of players that cross over from NFL to NBA and vice versa in a matter of months but put up decent statistics... If it really was ranked that difficult then it shouldn't be that easy to transition from completely different sports. (Not that I'm undermining the efforts of the players/trainers... but still)