Shortly they will determine that this was intentional — Putin giving the West the finger for its sanctions and saying that it was only a Malaysian jet this time but next time it might be Lufthansa or Air France.
The net effect of this incident is that Putin has forced European and Far Eastern carriers to now fly around Ukraine all together — costing them time and fuel and money and creating greater difficulty for east-west air travel.
I doubt it was intentional. They had shot down a Ukrainian cargo plane earlier in the week along with two fighters. They were just maintaining air control over the territory occupied by the pro-Russian insurgents. In war, sh*t happens. No doubt operational control was lax. It would be interesting to learn how far up the command chain the guys in charge of the missile battery had to go to get permission to launch.