It's not the words themselves but what they represent. What most of you don't understand is that people take offense to how the words are used. I really dislike hearing young grade school kids using profanity because they don't understand the half of what it means. Sure crap is the same as the word that begins with s in terms of websters dictionary, but think of the occasion it is used. If you want to say you need to #2, you'll usually just say you have to take a dump, etc.... But if you say the word that starts with s, then you know it's a different occasion altogether. Usually you're frustrated or surprised. You have the will power to say "Wow" or "Shoot" but instead you choose to use the other word. That's what makes it offensive, because you know some people don't enjoy hearing that word and you mentally have a vast vocabulary full of terms you can use instead, but you say that word instead. Typically because you think others will look at you funny if you don't say the "appropriate" swear word at the time.
When I was in 5th grade, I realized that I had used expletives to the extent that the words had no meaning to me. They had lost all usefulness to me. So for lent I gave up swearing.... and I kept that promise. Since then, I barely if ever swear anymore because I don't want to use profanity. I gained the capability to select another word instead. After all, it is just another word to you kids, right? If that is so, why use it if you know it irks another? I'm about 18 and find no pleasure in using profanity.
It can be related to why kids want to have sex at younger and younger ages. Drugs. Alcohol. Wear skimpy clothing..... the works. You young ones just want to be mature before the age that you should. You worry about peer pressure and just want to fit in. News flash, you're kids. If you don't know who you are, then you'll never know another. Likewise, if you can't be yourself, no one will ever truly remember you for who you are, just what you let them see.