"...And why are some of these terms so taboo, while more formal medical or scientific terms for the same functions are more acceptable? Is cursing a common feature of all languages, or is it peculiar only to some of them?"

I would imagine that in any culture which has taboos it will have swear words.

Using swear words in the "proper" settings is of course acceptable. In the book, "Einstein space Van Gogh's Sky" it bring up a rather obvious point that human daily enter different kinds of realities with different social rules.

Generally, the "Big Deal" with using such words as fuck, asshole, ect is in setting in which children could be present. And in audiences in which ladies are present. With children it was considered important to shelter them from "adult matters". Though if you and society in general are giving sex edu to six year olds, it becomes somewhat less significant. Though, probably most people would find it unacceptable for a strangers to bring up issues related to sexual matters when directly addressing children, despite the degree in which these children are familiar with these issues.
Of course another aspect about swearing around children is they will then repeat these words- and you probably wouldn't want your young child bringing up such language with strangers.
And there is the whole thing to do with how behave with friends and how behave with people you don't know- informal and more formal speech. Immediately treating strangers as though you were old friends, generally will cause them to wonder if they have somehow forgotten who you are or they may think you are crazy. And in various social setting the speed in which one can become informal can be quite fast or quite slow. A ballpark is different than a bus. A bar is different than a doctor's office.

Swearing is speech which is informal. If you start swearing at someone, one is immediately bringing the conversation to an informal level. If you speak formally to a friend, one is signaling that you wish to speak "seriously" with them about some issue. In informal setting "baby talk" can be acceptable if one is addressing a baby- but not a 10 year old. There is proper way to speak to pets. So there is all kinds of different rules for different situations and these rules can be changed over time and are different in different parts of the country.
And of course, on the internet if you use certain words, nanny programs will block you. And using swear words in the title line in the Habitable Zone is forbidden.