This is a very broad topic. A few concepts that relate to this are stereotypes, prejudice, and conformity. When we look at the concept of conformity we look at how each individual works to meet the expectations of the cultural group that they belong to. An example of this would be a woman defering to her husband's judement in a patriarchal culture. Conformity is when we are part of the group.
When we look at prejudice and stereotyping we are moving from the "us" to the "them". This is when we are looking at another group as an outsider to this group. When we stereotype we make broad generalizations and tend to not look at members of a group as individuals. When we are prejudice we assign behaviors to a group that may be negative.
When we take a "us" vs "them" approach emphasizing ethnic identity, there is not an appreciation for what different groups may bring to the table, this can cause segregation as well as hinder progress and new ideas will not be formed.
There is no objectively correct answer to this question. It is possible to argue it from both perspectives and neither can be proven true or false. Let us look at both points of view.
On the one hand, we can argue that some sense of ethnic identity is necessary in order to have social equality. From this point of view, a group that has no ethnic identity will not be respected by other groups. It will seem as if they have no pride in who they are and so others will not think that they are really all that important. It is necessary, in this view, to have ethnic pride and identity in order to be treated as equals.
On the other hand, we can argue that a sense of ethnic identity does nothing but lead to segregation and discrimination. In this view, groups that hold to their ethnic identity will never be part of mainstream society. They will hold themselves separate from other groups. If they are stronger, they will look down on the others. If they are less powerful, they will be looked down on. Either way, there will be no equality.
Both of these points of view make plausible arguments and it is impossible to know which is true.