Hundreads or maybe even thousands of flights fly over the region everyday. Its not the airline's fault for using that route. 

No, but it's possible with the tech the Russians have.

Or the Ukrainians, since they use the same kind of homing missile launchers.

Either way, it doesn't make any sense. It could have been a glitch on the tracking algorythms.

Hell, the plane could have fallen down on its own and we don't know it yet.

True. Civil aircraft usually continue to fly over dangerous regions. Planes still go above Syria and Iraq even with the situations in those countries. I guess that will change now after this accident. 

I think someone is targeting Malaysia Airlines. The first plane that crashed might have been shot down too.

Great. Now we have another Gaza on our hands.

I'm really not sure. I don't have much knowledge about missiles but something shot this plane down. Its not the first time planes have been shot down so I think missiles can reach that height. 

Early mod of the Buk SAM, which has technical capability to shot it, has been probably captured by the rebels, but that's not certain, and I'm not sure if they had all radar equipement to even spot smth at this altitude even if they had one. Earlier they relied on MANPADS, Strela-10 and ZU-23-2 only, this altitude is virtually unreachable for them.

The better question to ask why it even flew through this airspace, shouldn't it have been closed? I clearly remember it was closed. Have a strong feeling of dejavue behind all this. Seems like yet another blast of infowar, hopefully only "info" this time. Will wait for official statements on that to build any hypothesis.

BBC are reporting the missile would likely need to have been radar-assisted or perhaps launched from another aircraft to reach the MH-17 path of flight.

Airlines keep flying through dangerous regions because there are no threats.