I remember having quite a row with my exBIL because one of my DCs refused to kiss his mother goodbye.
He said, in that case he wouldn't kiss DC goodbye either.
I got rather cross at the idea that you withdraw you love from a child because they don't feel comfortable kissing someone. Horrible.
He seemed to feel it was a matter of 'respect' to kiss old people when they want you to.
My mother (born in 1908) was obviously pretty old when I had my children (now in their 30s and early 40s), she always said that it was unfair to expect children to kiss wrinkly old people as they are generally very unattractive.
Oddly enough my children always seemed more than happy to kiss her goodbye.
I also never expect my grandchildren to kiss me goodbye; sometimes they do, sometimes they don't.