All points that you guys have made are right in their contexts. For that I have no special opinion. What I see is probably from another angle, that is "do not to focus too much on preserving or changing one's culture", in other words, whatever customs stay with Chinese are Chinese culture, regardless where they are from. That is also true to all cultures in general.
A few examples,
Shang Dynasty was from north-eastern China, morden day northern Hebei, southern Inner-Mongolia and western Manchuria. They at that time (3000 years ago) are pretty foreign to the central plain which is 1000 km south. But Shang's ritual rites, court customs and institutions were followed by the succeeding dynasties. The mandate of heaven is the creation by Shang.
The Zhou Dynasty replacing Shang were people from very west at the fringe of Central plain, morden day western Shaanxi province, boarding to the "barbarians". They are pretty foreign to the then "Chinese" Shang dynasty. But Zhou built every fundamental concepts followed by following dynasties for 2000 years. The ZhouLi (周礼), the Zhou Rites.
The Qin who followed Zhou was another "semi-barbarian" who raised among the "barbarians" further west of Zhou's rising land, in morden day eastern Gansu. Qin people were known by the then "Chinese" Zhou and its vessels in the east as practicing some barbarian customs including Qin's ferocious war-fighting spirit which enabled it to eventually make China to be China as we know today. Its institutions were followed by the succeeding dynasties. And every Chinese today believe Qin is the funder of China.
Qin's contemporary counterpart, Zhao deliberately introduced barbarian's dress for its practicality of war fighting and Labour working. In the same way as today's Chinese dropped the traditional dress for daily life.
The second and probably the highest zenit of Chinese civilization was Tang dynasty. And Tang is well known in adopting "Hu" customs and practices, mostly from central and western Asia, Turks and Persians. Tang is also the height of Buddhism introduction in China. One may call Buddhism as part of Chinese culture, but it was totally foreign 1500 years ago.
One small but telling thing is that original Chinese dress do not use buttons. The usage of buttons was introduced from the step people. Who argues it is foreign today?
The list of examples are just too long to make.
My point is that, what ever practice that works for the need at the specific time in the specific environment will be part of the culture and tradition to last, where it was from, who made it first mean nothing.
I also believe that China is very willing to adopt foreign tradition that she see fit. Like it or not aside, the most significant adoption is Communism (to be mixed with traditions) and morden legal and social institutions all from the west.
All that I mentioned above are proofs that, Chinese is a great mix over 5000 years, the very core bearer of Chinese culture, the Han Chinese is itself a great mix within the bigger mix. There is nothing called "pure" in China, whatever stay with the people living on that land is no less Chinese than others. If one begin to examine "foreignness" inside Chinese culture, one will find almost everything is foreign at some point of time in the past along the historical path of China.