You are right, but actually, you are being nice (as in, limiting things).
A coworked said she and others once literally weighted the breast of a colleague of hers who had big ones - one kg each, two pounds, and given their position far from the center of mass, and that they are not a static mass, if you look at it from a point of view of physics (movement), they can have an impact, especially when it is a relatively small (as in "short", not talking about age) and slim that has big breasts (and for the skeptics, yep, there real ones, it is not only in Japanese games, though many of those game tend to really go overboard
).