And you don't think that Venezuelans, Peruvians, Colombians do as well? It would be interesting to see any specific numbers on that as I honestly don't think there's any difference between any of these nations as if they are in a "difficult" situation they would go to wherever they have a better opportunity, even if it means to go abroad illegally.
I just guess that the other countries have had better negotiators, and now it's just too late to remove any VISA requirements as that's how the world has turned to, "foreigners, uhh go away".
If people who has those ideas ever actually stopped for one moment and actually reflected how their life's have been enriched by the fact that the world is now more open than ever.. Ugh... So yeah, I don't think DR has any good chances to actually remove the VISA requirement, like EVER...