What is and isn't profanity has changed drastically over the years. Originally, profanity only extended to blasphemy (you had to speak ill of something holy or sacred, or you had to speak flippantly about religious figures or religion itself). Which means unless you were directly insulting or disrespecting a temple, religion, religious figure, etc. then you weren't using profanity. Hence taking the Lord's name in vain as one of the 10 Commandments - you were being flippant about God, which was considered profane, because He was to be respected, etc.
As far as English is concerned, most of our "profane" words are of Germanic/other descent, whereas the more appropriate terms come from Latin. This isn't by coincidence or mistake. This was a direct result of, first Romans, and then the Church's power over people. Romans would hold Latin in a higher esteem than the "vulgar" languages (which really just means the languages spoken by those who didn't hold a wealthy/politically sound position in society). Later on, the Church held Latin as the language in which all services and translations of the Bible were in. So therefore, Latin and words derived from Latin were better than words derived from other languages, because Latin was the language of the Church and others could be considered pagan or too secular to be used by higher society.
However, there have been dozens of linguistic studies and research into the use of swearing and the act exists in all human forms of communication (and even chimpanzees have their own version of profanity). It helps further communication with others and it even helps lower stress levels, increase tolerance for pain, etc.
So basically, there's nothing wrong with swearing (unless you're a Christian and you're taking the Lord's name in vain). It's a social construct to reinforced dominance and class striations by the Church and carried through by habit.
And there's absolutely no merit to the whole "sign of limited vocab/intelligence". Profane words are still words and still belong in your vocabulary, so you could literally know billions of words and still choose to use something others consider "profane". After all, sometimes, "ass" just suits what you're trying to say better than anything else.