Hi Paul,
I agree with you and I do the same most of the time. Because I have the Adobe suite.
But Eps is still very widespread for those who don't have it (the client who want a source file of your job for example). More other, I have many common works with a graphic who doesn't AD and is attached to the Adobe Suite. We need a good and simple way to exchange.
Ok, pdf could be the solution. But with the AD export tests I did, the colors where modified (you know when a value is transformed from 45% to 44.89%...) and texts became cut by letters and not by words (depending on kerning, line return, etc).
That's why the PDF/X export is so important.
But AD is a very promising soft and I will continue to learn to work with it.