Display Moreisn't Japan four times bigger than Korea if we look at land area itself?
not to mention how different places are there?
for example you have volcano in Kagoshima, beaches in Okinawa, most 'snowy' city Aomori
to add to that you have Tokyo, Kyoto, Osaka, Nagoya, not to mention bomb sites in Hiroshima and Nagasaki
but to add to that maybe real problem is that Koreans don't really know how to show their country well?
like what you can really do in Seoul? there are some nice places but that's one day of sightseeing...
if you want to see more you should go to Jeonju, Busan, Ulsan, Suwon, Gyeongju, Pohang, DMZ etc.
Agreed, Gapyeong is also great place to visit outside Seoul. 
