That is exactly what dictators do! Not perfectly, but a lot better than what has happened in the countries you've noted where the dictators were ousted or attempted to be ousted. So, I'd disagree that it should be a global interest to crush dictators. So far, this has caused much greater harm than good.
Dictators usually enrich themselves and defraud incoming money (and food aid) by pocketing it in their personal or their families' coffers, also most dictators resort to brutal violence to maintain their rule; as a result people will attempt to flee these countries. And this causes harm - first of all for the fleeing people who are often enough abused as slaves or prostitutes, but also by funding criminal networks (e.g. the Mafia, which has discovered that people-smuggling and involvement in refugee operations is way more profitable and riskless than drug trading).
Also, when we as the Western world fail to provide basic human rights to any person on this planet, when we fail to even TRY and instead make "deals" with those violating human rights, what are the human rights then worth?
I agree that the last few ousted dictators went badly, but more because the Western countries failed to provide an exit strategy, not because they attempted to oust the dictators.
The first South Korean leader, propped up by America, wasn't your average local warlord: Rhee Syngman was a prominent figure in the independence movement, and had a PhD in International Politics from Princeton.
He went on to kill some 200 thousand Koreans for being communist, terrorized the country for twelve years, and finally ousted by Koreans and fled to Hawaii, where he died later. His reign is remembered by corruption, blanket pardon to national traitors, and mass execution of people accused of being communists.
If you think you "only" need an exit strategy to liberate a country from bad dictators, you don't understand how much luck you need.
I'm German. Germany is only at it's current position as European power house and "leader of the free world" (at least many people name Angela Merkel als such, since Trump became president) due to the incredible efforts of the US, UK and France (and to a lesser extent the Soviets) after WW2. And Germany was bombed to shreds basically.
You don't need "luck" to succeed. You need political will, power and the ability to look further in the future than $time_until_next_election. Not very many politicians (no matter if in the US or in the EU) seem to possess these traits any more.
> He went on to kill some 200 thousand Koreans for being communist
Then, he IS a typical result of US intervention: everyone who is against "communists" is good.