There has been a rumour flying around for many a year, that when TCAS was mandated for European airspace, many companies fitted it, but did not train the crew either sufficiently or in some cases, at all... the mere carriage of the equipment is/was all that is required by the letter of ICAO rules. .... DISCUSS!!??
As for blame for the accident, like many things, it was many small errors that led up to the one tragic outcome. If any one of the small errors had not happened, chances are we would not be discussing this today.
However, despite not having suffered like Mr Kayolev has, it was still cold blooded murder. It happened well after the accident, surely this cannot be called a crime of passion or impulse?
If the Kayolev did, as suggested earlier in this thread, help arrange the trip, was his revenge an attempt to assuage his own feeling of guilt (which any human being would feel.... he must have been thinking "if only I had never arranged this trip etc". Amateur psychologists discuss!