There was a time, many years ago that Jamaicans preferred US dollars because they were unable to get them unless they had a bank account that allowed it. Today, they can get foreign currency just as easily as Jamaican Dollars.
I think the Jamaicans who tell you they "prefer" US dollars do so because you give them more on each transaction. They tell you "$100 US" on a $10,000J transaction and then they exchange it for $12,000 or more.
I think the "Jamaican Experience" extends to learning about the people and culture and the way they live each day and that includes their money. It is not so difficult to use Jamaican Dollars and chat a word of patwa here and there. It makes for a better experience in my opinion. No harm, no fowl if you want to continue they way you do it though.
Peace and Guidance