I think there’s good and bad to assimilation. Take a look at the US for example- they support assimilation of different cultures into the “American standard”.
Now, as you suggested, there are disadvantages to this- in the absence of a rooted cultural system one can lose track of himself as a person and what makes him a unique individual, and start changing his value system. But there are also some good points- in the US for example you gain access to a culture that’s globally accepted with values that can help you become successful in this world.
My opinion is that you should always trace yourself back to your origins and never lose your culture. However, you should also incorporate other cultures into your own if you think they have some good things in them.