The Capitol has had a holiday tree, provided by the Association of Washington Business, for 19 years. In 2006, it was joined by a menorah sponsored by a Seattle Jewish group.

That prompted a lawmaker from Spokane to stage a protest at the Capitol, demanding the holiday tree be called a "Christmas tree." It also led a local real estate agent to sue the state to allow the nativity display depicting the birth of Jesus.

Gregoire, a Democrat, and Republican Attorney General Rob McKenna put out a joint statement Wednesday noting that the federal lawsuit led the state to create a policy allowing groups to sponsor a display "regardless of that individual's or group's views."

and pretty soon, either everything will be there and it will all get ignored or, it will all have to come down because people are being stupid about it.

http://www.cnn.com/2008/LIVING/12/05/atheists.christmas/index.html?eref=ib_topstories

I've never taken any position for or against the "Humanist" doctrine, but now with more news (and media
attention) being out in the public venue, my feeling is that
if their beliefs and principles are so deeply held, why don't they have their own traditional holiday observances?

Because Humanism is a set of philosophical beliefs, but it's not a religion unto itself. It has no Deity, therefore no need for holy days.