Seriph wrote, ".... TCAS. The Russian crew ignored it ...."
I feel that you are simplifying the situation. From released transcripts ther was considerable confusion in the cockpit. he Eastern Block approach is to always follow the controller's instructions. Not having access to the ICAO docs at the moment I cannot check whether there is a published exception to the ICAO standards/recomendations on this.
PN made a judgement call, based on the information available to him at that moment. Tragically it was proven wrong. As many others have pointed out, "There but for the Grace of God ...."
Historically, it requires a tragedy of this magnitude to bring about improvements in the system, (e.g. the Grand Canyon accident in the 1950s).
I know that within 24 hours of at Maastricht there was a review of working practices and a number of changes were made, NOT I hasten to add, that they were unsafe in the first place. It was a case of belt and braces. I am sure that this action was taken world wide; whilst this is of no consolation to the families of any of the victims of this accident it is re-assuring that a similar occurence should not happen.
Aviation is an un-natural business and there is no way to reduce the number of accidents to zero - even were aircraft never to leave the stand there would still be weather related incidents and ground handling staff would continue to drive into them.
It is easy to point the finger of blame. The air traffic system would be completely different if it were run by controllers,or pilots, or systems people, or, as is the case, by politicians: almost all decisions are made retro-activally, not pro-activally, and the hoops keep lining up.