In case of South Korea, the very genre of "flight simulation" - whether be it civilian aircraft or military combat planes - is itself treated as very rare and eccentric.
Particularly if it comes down to WW2 fighters and planes, since this country wasn't a real combatant (although some very few soldiers did serve in (remarkably!) the German forces, and a lot of young men were forcefully conscripted in the Japanese military in the final days of the war) the interest in the genre remains very thin.
Another factor is that the aviation industry is very small, and people who can enjoy flying civilian aircraft as recreation is very limited. It may not be a strange thing to see people who own Cessnas in the US, but in Korea, where you fly off for a few miles from Seoul and you'd be flying around the DMZ, its very very uncommon to say the least.
The third factor would be political. A potentially successful theme would be the Korean War and the battles in the "Mig Alley", but the problem is there are still many political restrictions in depicting the military struggles that happened in Korea.
For one thing, saying truthfully, it hasn't even been 20 years since our country really turned 'democratic' - the military dictatorship lasted some 40 years, and right upto early '90s if anyone would have been caught reading books or seeing films that had anything to do with the Soviets, communism, or anything having to do with N.K. during the war, they'd be in for heaps of trouble (although not necessarily disappearing for weeks and then turning up dead, like things happened in the 60's, 70's, and the 80's)
When Falcon 4.0 came, it had to delete all the campaigns in game depicting struggles inside the Korean peninsula, and only then it was allowed to be published in Korea (which led to a lot of the flight sim gamers going for illegal/pirated versions of the game). So I'm not sure if a "Mig Alley" type of game can ever be introduced in Korea without having to worry about legal issues. We don't really have a 'rating' system - we have government censorship committees who judge which material can be published, and which not, according to (mostly) political agenda.
To the small, but devoted group of aviations enthusiasts in Korea, such as yours truly, US or Europe is like heaven.
