Why Not Remember The Formation of Malaysia?

Independence and formation of Malaysia are two different events. Malaya gain her independence from the British on 31st August 1957. During those years, the Territories of North Borneo was still under the British rule. These two states was freed from the British in 1963 when they were given the independance through them joining Malaya. Only then Malaysia was born. The formation of Malaysia is an important milestone for this country but why we do not celebrate the birth of Malaysia?