What you say reflects what many of us do. But it is ironic, because we are in a much better position to get great shots of the places close to home. And the locals in those European destinations are much more likely to be able to get great shots where they are.
If this was about getting great pictures, then the answer would be to buy a photo book of the location you are visiting. If it's about recording what you actually experienced while there, a P&S would suffice. But in fact for many of us it's about using our gear. We want to use the gear that we have acquired and treasure.
Speak for yourself. I don't care how many times a place was photographed, I like to photograph it with my own vision in mind. It might look like someone else's photo...but then it might be a very unique view of the same thing that was photographed thousands of times before.
That's sort of like saying...why paint, its all been painted before...just buy a book. Or why make music...its all been done before, just buy a CD.