I think that your view of cuss words is a little narrow. Using them adds a little bit of color to your speech I think. If someone used the words "go", "nice", "went", "good", or similar general purpose words, it indicates a similar lack of vocabulary (imagination), but from what I gather, you wouldn't consider it to be as bad as if the same cuss word was used repetitively.
The thing is that cuss words often have several different forms and meanings based on context, and that makes them powerful words. They can be strung together in many creative ways to produce one long line of profanity, which takes quite a bit of thinking on the fly. Using them in the right places can also enhance the structure of what you are trying to say. For instance, you might be trying to insult someone.
"You suck at the internet!"
Might be a simple insult thrown at someone. It becomes a little bit more powerful when a cuss is added:
"You suck at the internet ass-grabber!"
Just a simple (but very lame
) example of what I mean.