Not necessarily. They are also for commemoration.
Two very important holidays for Magyars are 15 MAR and 25 OCT (at least I think it is the 25th of OCT, how embarrassing for ME!). Both holidays commemorate important times of battle for Magyar people... The October rememberance is from 1956 when the civilians tried to fight off Russian tanks (communism)... unsuccessfully, but dammit they tried regardless of how the US promised to help... but DID NOT.
I dunno if 11 SEP should necessarily commemorated as it wasn't a positive thing for the US. I think that there should definitely be memorials and the date NEEDS to be remembered as Americans should pause and realize they are not as free as they had falsely been led to believe all these years. T'was tragic indeed, but no less tragic then all the other tragedies that go on regularly in many places around the world.