because nations are defined as sovereign and
limited.
no nation in the world hopes to include everyone else into its fold
and since nations are sovereign, they would not likely want to
forsake this sacred sovereignty easily to be incorporated into
another sovereign entity.
greater china, among other things, implies just that: a surrender
of sovereignty to another sovereign protector. whether it's a
cultural acknowledgement of a superior overlord or a political
settlement which states the status of states within this greater
china, it boils down to losing part of our sovereignty.
i am yellow skinned, but i possess in my blood other ethnicities
who have settled in this region for the past 200 years. in fact,
every chinese who is able to claim that their family has been here
since at latest the 1890s is mixed in some ways.
why? because Chinese women did not start coming in great numbers
until around that time! anyone born before that would probably not
be the result of a union between 2 chinese.
besides, has it ever occured to anyone that most chinese immigrants
came from the southern coast. much of the economic activity is
centered around the southern coast, but the Beijing elite are
mostly northerners!
u really think they will happily accept u into their chinese
brotherhood unconditionally? please...
its childish to think that yellow skin, a chinese name and knowing
the language guarantees u a friendly place in the club. it doesn't.
ethnic pride is one thing. national identity is quite another. u
mix the 2 at your own peril. 
