Why? They have what? One MP?
The issue is not a number of MEPs but an overall political symbol. German minority have lost all their privileges in Poland after most of them converted into 'volksdeutsche' and acted as a 5th column against Poland and Polish interests before and during WWII.
And a very good reason for Poland to keep its distance from such a merciless country!
And since we cannot keep a geographical distance we should maintain a political one. Nothing good ever came to Poland from Germany, perhaps except for potatoes.
Trading with Germany is fine. When it comes to modern culture and social life they've got nothing of value to offer to us. And geopolitically they're under American boot. Why would we talk with them if we can talk directly with the US?