Honestly, given the way Sentai works (and I mean real super sentai, Zyuranger not Mighty Morphin, Shinkenger, even Sailor Moon really) works I don't think you're giving a huge section of cultures enough credit.
Maybe some modern comics conventions may not be agreed across the board, to say that they don't get superheroes feels a little narrow minded to me, unintentionally so but still there.
Look at those -- it's a
group of characters fighting [insert opponent here]
together. Look at the type of MMOs that NCSoft makes its money on in Asia. Take
Aion, for an example; you have the starting zone, where there's little that a single character can't handle themselves, then the first zone after you get your wings, which is still pretty solo-friendly, although there's a monster roaming around the central town that wants a team to take down effectively, and when you hit the mid-to-late teens you start getting handed quests that are essentially unsoloable, forcing you into groups to complete them. Which isn't a drawback for the Korean players who get together with their gaming group to go down to the gaming cafe and socialize while they play, because that's the way their gaming culture grew.
In the West, gamers would go off into their computer room at home to play; it was a mostly solitary experience, and you would socialize
in game with the friends you made
in game, but if your friends or guildmates weren't on, you had the solo content to keep you busy; because it evolved from single-player games, PvP and the group content was generally an
adjunct to the characters' storylines, not an integral part of it.
With the exception of skippable parts of the game -- TFs, Hami raids, mother ship raids, Incarnate raids, etc. -- there was nothing in City of Heroes that
actively pulled players together in teams, and certainly nothing (aside from a leveling pact between two characters) to pull a group of characters together to play through the content together. CoH followed the Western superhero-comic style of the solo hero, who might become part of a group, but the fact that Iron Man joined the Avengers didn't stop him from going out on his own, or teaming up with another hero on an ad-hoc basis -- where in the super sentai programs that became the norm in Asia, the members of the group come together and fight
as a group; it is rare for a character to have much solo time. And that dichotomy made the gameplay style of CoH more foreign to Korean gamers when 'City of Hero' was released there; it didn't fit the superhero meme as it was presented in Asian media, even though there is nothing inherently
stopping you from playing CoH that way -- the game didn't resonate with Korean gamers the way it did for Western gamers.
City of Heroes was as amenable to getting together with a bunch of friends for an evening's play as any of the Korean MMOs, but it was a facet of the CoH community and Western gaming that we didn't think anything of playing with a group of friends one night and playing with a
different group of friends the next night, just from the vagaries of who was on at any given time. But what the Korean players wanted was a game that supported a group of friends getting together and
then gaming together -- socialization in person, not across the Net, with the group membership being stable over time. Neither one is better than the other, but each type will be jarring and less attractive compared to the playstyle you're comfortable with. And that's why CoH flopped in Korea, and why the Korean-style MMOs have an uphill fight to retain Western players.