If you insist they give up their culture immediately you will be seen as trying to take away their culture. Just like how gun rights advocates perceive attacks on gun culture.
Solidarity is a normal reaction to real or perceived hostility. In history the social pressure to assimilate resulted in immigrant collectivism in order to support each other; Chinatowns, little Italy and a myriad other ethnic enclaves formed partly because of this pressure.
Immigrants that go through the proper process of getting into a country are a totally different story. The country makes sure they will benefit society. The immigrants bring something to the table to benefit the society. They want to join the society, and have something to gain in the success of that society. They do not have plans to simply leech off of the host society.
What we are currently dealing with, is unrestricted immigration. They are just flooding in without any regard to their benefit to the society, or even their motives for coming into the country. This is a slap in the face to the real immigrants that spend so much time and money trying to get in through the system. They see these other immigrants just walking across the border without having to jump through the same hoops.
I don't think many people have an issue with proper immigration. But the current immigration problem is something separate. There is no regard for the host society.
Immigrants that want to join a society are expected to assimilate, because they want to join the society. If they like it so much, assimilate. If you don't like it, stay out. Its very simple. Its not racist. Its not what-the-fuck-ever-phobic. They made the decision to join the society. They have an obligation to assimilate to that society. Otherwise, stay in your current society, if you love it so much.