I'll come in a little harder.
Carriers who have a good background in worldwide operations and understand what "Risk Asessment" really means seem to have been the ones to make their own decision to route away.
From past experience on this exact routing, there are carriers who route around poor weather etc (and this can be seen on the in-flight map), and those who just plough on straight and put the seat belt sign on. Notably there is a correlation between those who take this second approach and those who were still routing over Eastern Ukraine.
a fly around wil add approx $18000 to the flight
That's a ludicrous overstatement. For the 275 pax on board that's an extra $66 cost each. Given the prevailing fare levels on AMS-KUL that's about 20% of the typical one-way fare. Costs of taking a parallel airway with a 5-10 minute penalty on a 14 hour flight would be nothing like that.
especially when told you are safe above F320
That was never said. It was that up to FL300 was closed due to military threat. A world of difference.