I've heard as many reasons for going braless as for not going braless, which tells me that the decision is complicated and mired in societal expectations.
I personally find bralessness to be of ultimate comfort. What I had to get over was my self-consciousness of being braless in public. That took time. But was well worth the effort when I consider how much nicer it feels not to have my breasts supported' into a fixed position all day.
And I had to get honest with myself. It wasn't that my breasts preferred to be strapped into a bra an excuse you may have used yourself but rather my fear of not following the status quo. According to your North American fashion tradition, women wear bras. Why? Because if we didn't, an entire industry would collapse. Don't kid yourself. Bras are an invention, not a need.
Experiment with bralessness. If you are unsure, start out around your home. I found that after a couple of months, I was venturing forth, slightly self-conscious but not enough to stop me. No one seemed to notice. Now, several months into my experiment, I rarely wear a bra. Rarely equals once a week, for a short period of time because of the clothing I've chosen, not the occasion.
I see this as wonderful self-development. Be brave and give going braless a try.