Well, the PDF option isn't really a good one for me. Our ERD's are a little too big to be easily readable in that format without some serious taping. The HTML option has been around for some time, though. I don't know if it was in the releases ~ 1999/2000, but if not it was pretty close to that point.
As for the licensing, I'd much prefer a concurrent user type licensing for the most part for tools like this. We just don't have that many people who are going to access them regularly. However, that is a significant cost increase over the single-user/pc license. I may need to check out the all-access license to see what the differences are. That may be worth it for us.