I've always been under the impression Cowboy Bebop is considered anime for people who don't like anime. Not that anime fans hate it, but there's ones they'll find far better, and its crossover appeal means it's not really a good measure of the genre. There's certain far more obscure works that one can use as a benchmark to identify an anime fan, but someone saying "I like Cowboy Bebop" doesn't identify one as such flat out. Kind of like someone claiming to be a fan of Hayao Miyazaki, although to be fair the distinction here is more between simply liking Miyazaki's work (which plenty of people not fond of anime otherwise do) and absolutely LOVING it (like the die hard anime fans do.)
Oh don't get me wrong, there are plenty of anime pieces that I (personally anyway) enjoy more (Evangelion, 5 Centimeters Per Second, Steins;Gate, Eden of the East, The Big O), but whatever the case may be, one cannot deny the influence shows like Cowboy Bebop if only due to its crossover appeal, which if you think about it, is partially why Avatar is on this list in the first place.
