"Continued hostility with the DPRK doesn't make any sense either...Why not get rid of the problem by mollifying Pyongyang?"
1. Some of us might find it just a teeny bit morally reprehensible to mollify a government that employs concentration camps for political prisoners, kills its own people, allows no sense of liberty, IS arguably as close as we've ever gotten to an Orwellian State, has hurt innocents from Japan and South Korea, has nuclear ambitions (even if they can't yet be nearly realized), is as anti-America and anti-West as they come, is about as oppressive a regime as there is on the planet, and is on the whole quite arguably the single worst country in existence today, period.
In short--there are HOW many countries that could use our aid right now...and we'd instead give it to one of the very few countries that would most assuredly bite the hand that feeds it?
2. Leaving aside those moral qualms some of us might have...
"But let's just say most people agree that appeasement with DPRK is out of the question, whereas appeasement with Venezuela may not be."
+1 TheMinisterofWar--that, right there.
If we're going to appease a nation, I'd rather it indeed be one like Venezuela or, as the Obama administration has attempted (albeit with admittedly extremely-mixed results at best), some of the Arab nations we keep having issues with.
Change is more plausible in those cases, and there's less of a track record to work against than the Kim Dynasty (you may be OK with it, Putin, the rest of us are not.)
What's more, mollifying the DPRK could upset or otherwise bother two important strategic and economic allies, South Korea and Japan...and what would we get in exchange but mollifying a bereft, starving, cruel Orwellian state that we have no reason to believe would change its position, anyway, it's track record (not to mention its human rights record) is decidedly against it.