I have lived in Santo Domingo for many years. I have visited many other small towns. They are just too small for me. I don't want to see the same people every day or go to the same stores every day. Santo Domingo has the variety I like. Life is not so bad without a car. I live near a Metro stop. I also use public cars during the day and taxis at night. I could not stand having a car with all its built in problems. The traffic and all different forms of the police would quickly send me over the edge let alone always being at fault when in an accident. I have a backup system for lights and water, reliable cable and internet. I have a trusted Dominican employee who deals with all problems . Actually, I find life pretty nice in Santo Domingo.
If I were to live at a Metro stop and only needed to move around downtown SD, I wouldn't need a car - just like you said. But in the outskirts, like Villa Mella or Los Minas, it's not easy without one I can tell you. At least not with a toddler that can't take as much heat, exhaust fumes and noise as we grown ups.