Because some westerners are ignorant to the facts.
why do some westerners view the east or asian civilization as primitive or barbaric?
Not some almost all westerners do? It is because Asian, eastern is the oldest civilisations and it makes them feel small and uneducated hence the smear.
Hi there! Ignorance is the roots of most of the world’s evil and you just mentioned a very good example! Westerners are too proud of their countries, but the thing that they do not realise is that their ancestors went on to loot eastern territories like India and China to get the riches that they used to develop their land. It’s a shame!