>>There was a screenshot of the radar situation a few minutes before the event (taken by, I assume, third party - all the markings were in english), and there were two more unidentified planes nearby. Some theories state the possibility that an ukrainian army plane was trying to stay in the civilian craft's shadow, was shot at, civilian craft was hit.

That might explain it. FWIW, I'm only a civilian but if people know that poorly trained rebels have anti-aircraft missiles that can reach up to 70,000 feet and have been firing at aircraft, I'd be inclined to take a different route. Granted that Ukraine is the more direct route from Europe to Asian cities and that avoiding Ukraine completely could add $20,000 to the flight cost, but if you insist on crossing Ukraine then at least stay away from known conflict points, surely. Why not stay hundreds of lateral miles away from that contested Northern part? Then nobody will want to shadow you or shoot at you. I guess some or all of this may be revealed in due course.