NK, like East Germany before, operates on the claim that they are the only legitimate rulers on the peninsula.
In 1950, both sides made that claim, but the fact remains that the west had given little thought to the important question of what to do with Korea after WW2. It is claimed that F. Roosevelt thought that it may be 50 years before they could rule themselves. By the time that Japan surrendered Russian (as the USSR) troops were inside this former part of the Japanese Empire, an well down the peninsula. The American command made a belated offer to the Russians to divide Korea into two. During the one year I spent studying Korean hiistory, I never found a satisfactory answer to the question of why the Russians agreed to the American proposal. Anyway, the Russians set up the DPRK under Kim Il sung, supposedly a former guerilla fighter against the 35 year long Japanese occupation.
The Americans set up the Republic of Korea, parachuting in a staunch anti-communist named Syngman Rhee, At the time that the Korean war commenced both sides were marching battalions of soldiers up and down the border. Who jumped first is not clear, but of course, most western sources claim the north did.
By the time the Americans got themselves a bit organised the DPRK, had pushed the ROK/American army into a corner around Busan. Macarthur's (quite brilliant) counter attack with an amphibious landing at Inchon, well behind the front line nearly brought about the rout of the north. Macarthur failed because he decided to ignore the Chinese warning not to drive through to the border area. When Macarthur ordered his forces to do just that, the Chinese entered the war, moving at night they took the Western forces by surprise and soon the American/western forces were fleeing south.
There is a reasonable description of the war in Wikipedia, https://en.wikipedia.org/wiki/Korean_War.
There are some differences in that account and my own, but essentially both tell a similar story.
Waton: They never formally surrendered to the overwhelming looming western might.
"overwhelming looming western might." Is that why there was a truce, rather than a ROK/USA victory that steamrollered over the whole peninsula? Many observers think that it's the USA that has been slow to keep a final peace treaty from being signed.
How would the view you espoused fit in with ...
"The Agreed Framework between the United States of America and the Democratic People's Republic of Korea was signed on October 21, 1994 between North Korea (DPRK) and the United States. The objective of the agreement was the freezing and replacement of North Korea's indigenous nuclear power plant program with more nuclear proliferation resistant light water reactor power plants, and the step-by-step normalization of relations between the U.S. and the DPRK. Implementation of the agreement was troubled from the start, but its key elements were being implemented until it effectively broke down in 2003"
Why did this agreement break down? Who obstructed it?
Soon after the agreement was signed, U.S. Congress control changed to the Republican Party, who did not support the agreement.[16][17] Some Republican Senators were strongly against the agreement, regarding it as appeasement.[18][19] ... From 1996 Congress provided funding, though not always sufficient amounts.[11][21] Consequently, some of the agreed transitional oil supplies were delivered late.[22] KEDO's first director, Stephen Bosworth, later commented "The Agreed Framework was a political orphan within two weeks after its signature".[23]
Some analysts believe North Korea agreed to the freeze primarily because of the U.S. agreement to phase out economic sanctions that had been in place since the Korean War. But because of congressional opposition, the U.S. failed to deliver on this part of the agreement.[24] "
In other words the American side, (not the DPRK) could not fulfill its part of the agreement.
waton: Think of a united Korea with the aspiring North's military and the South's economic clout.
I doubt that will happen, there are too many historical and ideological differences. But the over-riding reason is the cost of such a move. Some calculate the cost to be as much as three trillion dollars.
The correct solution is to give the DPRK a reason to believe that they have some security of tenure, and support the current DPRK trend toward developing a market economy. As a middle class grows (who have an incentive to support a peaceful future) the problem will be solved.