Most of unification-at-all-cost crowds are left-leaning. The political left co-opted the issue of unification as their own. This view is of the third world left-wing ideology, which is big on national liberation and anti-imperialist struggle.
Many do not realize that they are duped by these leftists. They think that denouncing the previous military dictatorship is perfectly OK but denouncing the N. Korean regime is anti-unification, reactionary behavior.
They also think that N. Korean regime thinks like they do on the issue of Korea and her future. Nothing can be further from the truth.
That is the part that I've never been able to figure out. The unification types seem to intellectually realize that North Korea is a bad place lead by bad people. Emotionally they seem to think that Koreans would never really want to hurt other Koreans, and that reunification would solve the North / South differences.
"If only Korea was unified, then the war would end, the Americans would leave, and the land would be healed."
A fairy tale, perhaps, but after living for fifty years under the threat of war and death, an understandable one.