You asked the question, so nobody shoot me for answering. Also please note I use the word "generally", and there always someone who is an exception.
I have to admit my tastes are changing, in the past big was always better in my view.
But...
then after having a partner with DD's for quite a number of years, you feel the pressure - unwanted approaches.
Simple fact men are attracted to women with big boobs, and whenever your back is turned there is some other guy hitting on your partner. It doesn't matter if they're attached or not.
That simple, and at all levels from very small moves bit by bit over time, to outright flirting.
On a second note, small boobs generally mean for a more sporty, physically active woman (or not), who then gets out in daylight hours to do stuff. I have to assume big boob-bounce is uncomfortable when jogging and stuff. I know I like everything snug and secure when I'm mountain-bike riding or running.
My2 cents