A few thoughts
AZB, compared to what is Costa Rica over-rated? Not necessarily disagreeing, just wondering.
You also quickly gloss over noise "pollution". In the DR it is not "pollution" but planned. There is no way to escape the sound trucks, or boom boxes, or trucks and buses blasting with air horns (even when stationary), or music being cranked up far above the threshold of pain. I believe that Dominicans' normal sense of hearing is destroyed at a very young age, perhaps while still in the womb. I haven't been back to Costa Rica in about 10 years, but I don't think TICO's would allow the same amount of such torture as in the DR.
Also, the smog in San Jose is greatly exacerbated by its being in a valley surrounded by mountains. It is not necessarily due to a lack of concern. Compare it to Phoenix, for example - it is simply hard to do anything about it.
I am also amazed that no one else has referred to the climatic differences. I suspect that I am not significantly older than most people on this board, and I find that as I age I am ever less tolerant to heat and humidity. San Jose is always comfortable, but even the Pacific coast (I haven't been to the Atlantic one) is significantly cooler than the DR.
Concerning the climatic preference maybe somebody can explain it to me. Even Scandinavians only spend a half hour or so at a time in the sauna, so what's so great about the constant sauna in the DR?
Again, just thinking and wondering.