Kissing is, for me at nearly 70, my favorite sexual activity, just because it is the most personal. What makes it so personal IMO is more than just nerve endings, though the multiple sensory channels do give it quite a kick, but (1) the fact that faces are so much of what identifies us--kissing your face is kissing you far more than kissing breasts or vulva--and (2) the fact that our eyes are where our consciousness is centered--kissing feels like diving into the totality of one another.

You also make a great point about casual kissing. It's so friendly! I love being with a woman who is generous with kisses. Makes me feel warmly accepted, even when I know sex is unlikely, and increases the pleasure of whatever else we're doing together.