Someone at LucasArts has a sense of humor

From the Star Wars Databank entry for [Kashyyyk]:
With the rise of the Empire came a terribly dark time for the Wookiees. At the advice of unscrupulous Trandoshans, the Empire blockaded Kashyyyk and enslaved the Wookiees, using their brute strength for labor. So devoted were the Wookiees to their homeworld, that many would brave the blockade to revisit their cherished forests for key Wookiee holidays. (emphasis mine)

That last bit is a reference to the ill-conceived Star Wars Holiday Special, Lucas's first attempt to cash in on the popularity of Star Wars with an idiotic spinoff.