I can't make a statement as far as the legal ramifications and requisites (you might want to try the "Legal"-Forum to get a professional answer on that one.)
However, I seem to see only very few game rooms. A small one just opened in a Victorian house next to "El Listin Diario" on Beller in Puerto Plata. Compared to how many places like these are around in other countries (EGA: Spanish cities, have them on almost every block), there seems to be really not much going on in this biz around here. Niche biz? I would not jump onto conclusions just yet. I think however, whilst Dominicans just love to gamble the culprit may be that pin ball machines are "for amusement only"... they don't promise a payout... and for amusement we have the beaches, music, Flias (plenty) and lot's more.
... J-D.