Expletives just aren't fun to hear every now and then. It's probably not because there's anything intrinsically bad about them (it's just a sound), but we've been trained since we are young that they are "bad" words. And to some extent this is true, many expletives do ave "bad" dictionary definitions, but in the context they're used the meaning is never (or rarely ) implied.

I can see here that many people want to change this, and make expletives a common part of daily usage; but I don't see being a good thing overall. A lot of people hold to former way of thinking (that they're bad), and if you get into the habit of using such words it might affect you ability of form relationships with the majority of people who think they're bad.

In addition I think, even internally, it's hard to get that idea from years-of-training (and one that's held by the majority of society) out of your head. I know I'm probably going to be criticized for this, but using myself expletives gives me a "dirty" or "uncivilized" feeling. Finally, I also don't think they really add to a conversation in any significant way. There are much better words ou there (and more eloquent sounding ones, too) to imply emphasis (I presume this is the primary use-case of expletives), and a conversation does sound more "intelligent" and "cultured" like so.