[mstaoru]

I think the misunderstanding here might be "skilled people who come to work in Germany for N years" (which Germany sorely needs) vs. "people who immigrate to Germany forever to make it their Sacred Motherland" and bring their grandma and 3 cats.

As above comment mentions, N-years people sometimes have circumstances that make language learning difficult. My initial comment proposes to be polite (in my own definition, admittedly) and make effort to include them in conversations (in work environments - you do you in social env), especially when all parties know that all parties can speak perfect English.