So? The common language and language of inter-ethnic communication should be Polish
'Should be' but isn't. People studying oin a degree course in a language that isn't their own (English) are generally too busy to study a Slavonic language at the same time, unless they're going to stay, in which case they do of course learn Polish.
a tool of economic oppression.... and/or a vehicle of chain migration
'Economic oppression' is hardly unusual for students, especially while capitalism is unfortunately allowed to persist, and 'chain migration' is the way the world works - thousands of Poles have done this over the last century or so..
Fortunately, the number of courses offered by Polish universities in English, as well as the growing number of part-time jobs available to overseas students will hopefully attract more interest.
Poland is a great place to study, and also to settle down afterwards.