Maybe because we already had this one in July:
http://www.reactos.org/pipermail/ros-dev/2009-July/011896.html

As I'm not a Win32k dev, I shouldn't argue about technical details. But I
still don't believe that all the points expressed in e.g.
http://www.reactos.org/pipermail/ros-dev/2009-July/011933.html are suddenly
invalid, so that we can easily say that Arwinss is "the better
architecture". For me, it looks like the slides want to give this
impression.

Of course, I also want to see ReactOS going forward and Arwinss can surely
help for now. But simply accepting it as our new official Win32k
architecture.... I don't think we can make it that easy after all previous
opinions.