Interestingly, the Chinese and Japanese don't have spacing... but they get along fine
As for the Chinese -- well,... when your words are pictures spacing is a bit moot
And if not for Kangji the Japanese would probably be spacing things too.
According this professor of Korean language(
http://www.youtube.com/watch?v=vRUCdz92TKE ), the practice of spacing between words in Korean officially began with the publishing of the 독립신문 (Independence Newspaper) circa 1896, although examples of such spacing exist in earlier texts dating back to before SeJong created Hangul, there appears to have been no official grammatical rule. He goes on to say that a great irony is that now it can sometimes be said that newspapers are the worst offenders.
These two sentence are perhaps the most classic example of why spacing is important in Korean:
아버지가 방에 들어가신다 -Father went into the room.
아버지 가방에 들어가신다 -Father got into the suitcase.
A few more (from the video):
오늘밤 나무 사 온다 -
I'm buying a tree and bringing it
home tonight.
오늘 밤나무 사 온다 -
I'm buying a chestnut tree and bringing it
home today.
오늘밤 나 무 사 온다 -Tonight I'll buy some white radish and bring it
home.