What Are the Causes for Losing Varieties in Languages and Cultures?

Every human society has a culture that includes arts, customs, language, etc. Every culture changes and the main causes for losing varieties in language and culture, in my opinion, are: contact with other cultures, and development of science and technology.
When two cultures have continuous contact with each other, the two cultures may blend or adopt their cultural traits, such as language, clothing, etc. thus losing their individual cultural varieties. When people of one culture who move to a country where another culture dominates may give up their old ways and become part of the dominant culture. For example, groups of people from many countries have settled in the United States. Most of these people gradually abandoned the way of life of their homeland, and adopted an American way of life. They learned the language, adopted the customs, and followed the traditions.
The development of science and technology, on the other hand, may attribute to changes in a culture. The invention of steam engine, for example, produced great changes in the way people lived. The invention of the computer in the mid 20th century has also had enormous impact. It has brought far-reaching changes in communication, education, entertainment, and numerous other areas of modern life.
In conclusion, to lose varieties in language and culture is to lose richness in them. Therefore, to my mind, multiculturalism should prevail in the contemporary world, so that ethnic groups can bring variety and richness to a society by introducing their own ideas and customs.