As a little tyke my hair was curly. Strangers would sometimes touch it unasked when I was in a public place. I did not like that, but somehow understood it was OK or tolerable.
Signs of greeting, affection and admiration have fashions. Traditions and etiquette change — permitted and expected behaviors are culturally variable. Is shaking hands a good thing? Hands spread disease, we are now told after generations of such clasps. I suggest they should be discouraged but people insist on them, even doctors and nurses. Hugs can be gestures of warm friendship or they can be pushy invasions on one’s body. In some places kissing is polite and in other places despicable.
Touch is powerful. Physicians have been told that patients expect touch and that it can be healing. Babies need to be held in order to develop well. Faith healers touch as a form of blessing. Some rituals involve touching with water or oil.
Little of social touch is specifically sexual but libidinous arousal can be in the mind of the toucher or touchee. One, both, or neither person in a touch can perceive sexual intention; and one, both, or neither can like or want it.
A touchless world is cold and isolating, but a touchy culture can be uncomfortable and physically dangerous. Let’s try to be polite about it and ask when doubtful before presuming.