Poles desperately want to blame anybody but themselves. A Russian saying: "give them a finger, they'll chew off the whole arm".
Lena.Kiev, I appreciate your candor. There is a long history of animosity (and hostilities) between the Russian and Polish people, though this is not the place to debate which side is more at fault for that dark history.
What seems important is to recognize that deep-rooted biases--such as your statement above illustrates-- exist and may hinder fair consideration of the entire picture. Biases exist in nearly every culture. Awareness of one's own bias is an essential step toward overcoming it.
It appears to me that the Polish investigators properly assigned most of the blame to failings by the Polish Air Force, pilots, etc.
Yet to be a useful investigative report, it seems proper to consider all of the holes in the Swiss cheese, and what may have contributed to (or could have reduced the likelihood) of this tragedy. The report would be incomplete if it entirely excluded any deficiencies or potential contributing factors occurring on the Russian side, and recommendations on how such a tragedy might be averted in the future.
That doesn't mean the report is blaming Russia for what occurred.