as for public displays of affection, I find them kinda nice sometimes. It is always nice to see a young couple in love, people caring for each other, a passionate kiss between lovers and genuine happiness that only love can elicit. The world is so dark and gloomy sometimes, so I find that seeing others happy can brighten my day, and often make me miss my girlfriend when she is not around. I don't advocate hardcore sex in the park, but a warm embrace and a loving kiss can makes others feel good to if they think about it a certain way.
Generally speaking, all taboos are nothing more than social constructs human have created for various reasons, usually religious reasons. Take incest for example. This is taboo because we are taught that it is wrong, but if we were not taught it was wrong, it wouldn't be taboo. Humans are the only species that have taboos, and I find that peculiar and interesting. For example, Komoto Dragons have a survival mechanism that allows a single female dragon to start and entire colony by herself. A female Komoto Dragon can fertilize her own eggs, but only the male eggs hatch. From there the males grow, develop, and eventually reproduce with the original female, their mother. From this act both male and female eggs can be fertilized, hatched, and then reproduce with their parents, brothers/sisters, and aunts/uncles. In this fashion 1 female Komoto Dragon can start an entire population of dragons. This species has no quarrels about incest, and the same can be said for other species. Not only incest, but other taboos too, such as cannibalism, interspecial reproduction, etc. the human mind is fascinating and beyond comprehension. From this, we have concocted society, rules to govern that society, and even social expectations from others on a daily basis. This is something unique to the human species, and it will always be with us as long as we are together in society. I would even go so far as to argue that taboos exist out of a fear of judgement by others. Taboos are broken every day, maybe even every hour (just surf the internet for 5 minutes and you will get the general jist), but the people who break these taboos do not display them to the public (aside from the people on the internet I just told you to look up ... moving on). We humans are ok with breaking taboos but we are not ok with others finding out about what we do. We do not care about taboos, we care about being judged, shunned, and outcasted from society.