If you are a stranger, especially a man, perhaps especially in a group of other strangers who are men, and you come up to me and say, "You're very beautiful. I'd like to touch your breasts. Would you mind if I did?":
You will put me in fear.
Because you could be someone who will go away quietly if I say no (which I will). You could be the exiled gay prince of Farlandia, cursed to wander this Earth looking for the key to his return that can only be revealed by touching the breast of a willing stranger, and who isn't enjoying this at all. You could, in short, not be a danger to me.
But how am I supposed to know that?
How am I supposed to distinguish you from the person who says he's really just whatever, but is actually going to put emotional pressure on me, or make a scene, or stalk me, or rape me?
I can't. Because that would require a level of discernment and of trust that is not possible, by definition, in my dealings with a stranger.
And therefore, if you ask to touch my breasts, you will frighten me.
If your goal is actually to make a better world, I suggest that you use a method that doesn't involve putting women in fear.
(Also, I find it hard to believe you can create "the kind of world where [people can] say, 'Wow, I'd like to touch your breasts,' and people would understand that it's not a way of reducing you to a set of nipples and ignoring the rest of you, but rather a way of saying that I may not yet know your mind, but your body is beautiful," by going up to women, touching their breasts, and then going away. Among many, many other problems that are noted in the comments to the original. But that's secondary to my main point here.)