Not a lawyer myself either, but there are a few problems that greatly affected decisions to change:
(1) The XFree developers had a lot of internal squibbling. There have been a lot of times where the XFree developers refuse to accept popular, community-driven changes to the code
(2) The license is most likely incompatible with the GPL, which is a problem for a lot of client-side software, since the software linking to it would violate the GPL by becoming more restrictive.
(3) The decision was made without discussion, without consideration for the burden placed on the OSS community to comply with it. A lot of changes are involved. Even if the changes could be made, being incompatible w/the GPL makes it virtually impossible for most OSS software to link with it. This is a big problem for distros. Although I don't understand the legalese, the specific "advertising" clause, as it's being called, is incompatible with GPL's looser requirements.
Check out http://www.xfree86.org/pipermail/for...ry/003974.html
, a discussion involving RMS, Xfree developers, and others.
EDIT: From what I could find, here's the problem. The new XFree license states:
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution, and in the same place and form as other copyright,
license and disclaimer information.
3. The end-user documentation included with the redistribution,
if any, must include the following acknowledgment: "This product
includes software developed by The XFree86 Project, Inc
(http://www.xfree86.org/) and its contributors", in the same
place and form as other third-party acknowledgments. Alternately,
this acknowledgment may appear in the software itself, in the
same form and location as other such third-party acknowledgments.
But, the GPL states:
You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
From what I can tell, part (3) is the problem. The XFree clause is a further restriction on the recipient's rights, and is thus in violation of the GPL.
EDIT2: Found http://www.serverwatch.com/news/article.php/3315371
. It confirms tha the problem is that any code "substantially" linking with XFree code must contain their "advertisements", thus making it less than completely free to reuse.