Mozilla Corp asked that this be added in order for us to continue to call the browser Firefox. Since Firefox is their trademark, which we intend to respect, we have the choice of working with Mozilla to meet their requirements, or switching to an unbranded browser.
It's strongly our preference, and that of most of our users, to have Firefox as the browser in Ubuntu.
I think it's perfectly reasonable for Mozilla to have requirements and guidelines for the use of their trademark - we have the same for Ubuntu, and many other free software projects do the same. I would in fact consider it a best practice to have a good brand on a free software project, which means having trademark guidelines.
That said, I would not consider an EULA as a best practice. It's unfortunate that Mozilla feels this is absolutely necessary, but they do, and none of us are in a position to be experts about the legal constraints which Mozilla feels apply to them. We had extensive conversations with Mozilla in order to find the best possible way of meeting their requirements while preserving the flow of use of the system for our users.
Please feel free to make constructive suggestions as to how we can meet Mozilla's requirements while improving the user experience. It's not constructive to say "WTF?", nor is it constructive to rant and rave in allcaps. Your software freedoms are built on legal grounds, as are Mozilla's rights in the Firefox trademark. To act as though your rights are being infringed misses the point of free software by a mile.
I believe we have a new package in Intrepid, called abrowser, which uses the codebase behind Firefox without invoking the Firefox trade mark.