I posted the videos so some of you (which have never been to Colombia in the first place) could grasp that Spanish is not the same all around each and every LA country. In fact, Colombians from different regions also have some hard times understanding each other due to those same regionalism traits.
"Prettiest Spanish accent" is hardly how 99% of Spanish (generic base from our past colonial times) speakers today would identify the majority of Colombians in their "talk". Simply put, most that today reserve a label as "Prettiest Spanish accent" to Colombians have only come to meet and hear the social sectors from that country, which are from the main cities and most affluent economically. Therefore one can easy see how they are more used to stick that label onto Colombians, rather than having had the opportunity to travel and interact with the majority of Colombians there. Even with advanced Spanish they would have a very hard time trying to make sense of what's said to them from the Colombian regional talkers. I was born to Spanish and can say that my oral skills in that language are excellent. Even with all that, I DO have a hard time understanding most Colombian accents/talk in the regions as shown above in the videos. The same happens in Mexico, Argentina, Chile, Peru, etc...
By far foreigners that move to LA countries find the varied accents/talk in the countries they moved to, very hard to master and be able to communicate with certainty around the regions. In contrast, foreigners that move to LA nations like Cuba and DR find it very easy to travel, live and go about their biz in the country with just basic Spanish skills. Nations like Cuba and the DR were for a long time portals to the old world traveling towards the new one to the west, as such they became melting pots and refined the accents/talk to the bare minimum in oral skills.
As for "broader vocabulary": Are you for real!!!!!??????
So that means that people in the UK are masters of English, given how extensive of unused lexicon there is in the USA from their former colonial masters...
Each LA country owns their set language, that's why there's Dominican Spanish, Mexican Spanish and so on, when you select the language options in a computer.
The same happens with English, French, etc...
What you perceive as "bad" Dominican Spanish is the same "bad" English people from the UK hear from regular Americans (or so you think alongside those people that think on that line).
I would pay good to have one of you here talking about "Prettiest Spanish accent" and "broader vocabulary" move to one of Colombia's notorious majority regions, and try to make two and two of what you must deal with as they talk...
That would be priceless!!!