I think it is because eating milk-products is not part of their culture. they have their soy milk and tofu and stuff. and (i think) many asians are allergic to milk so cheese didn't really become popular in japan.
as far as i know^^
Actually it is much easier to find milk than soy milk here in Japan.
Milk, cheese (though processed cheese is more popular than natural one), yohgurt, cream, you can find them in ordinary supermarket without problem.