I know that Yom HaShoah was chosen by the israeli government, but I'm not Israeli, I don't live in Israel, and yet I still attend Holocaust RemembranceDay events every year.  Of course I think it's of great importance to give honor and respect to the six million Jews who died at the hands of the Nazis.  But there's no reason that has to be done without acknowledging the other groups who suffered.  As for International Holocaust Remembrance Day--I've lived in four countries on three continents, and I've never heard of anyone marking that day.  I'm sure people do, but Yom HaShoah is, as far as I can tell, the day used for Holocaust Memorials all over the world.