its not about its celebration! its about its legallity juridically point of view. The messagers of God is sent to us to mend our lives to give us and show us the right path which is right and which is wrong, and give us the guidance the Islamic deen is already completed and finalized.
we then the later generation has to follow this guidance. it is not about following our forefather or the tradtion of the old. but the correct deeds that is acceptable to God and what had been showed us by his messager.

other wise if we people all our tradion in this world is correct and acceptable to God, then God should have not sent hundreds of prophets and messager. for what?
lets just reflect for awhile.contemplate...