What is the deal with swearwords?

Many swearwords have the abusive meaning only when used in certain context or cirstances. So why did we make them improper in conversation when their primary meaning is innocent? And then we replace the explicit word by more acceptable one. Those words then become as frequent in our speech as the original swearwords were. So why should we use „shoot“ instead of „s**t“ when in both cases we don´t mean the word but just some kind of complain? Don´t have me wrong, I don´t feel comfortable using swearwords and i don´t mean to defense the use of them. I would just like to read some other opinions on this…