The answer can be found in the plane crash of Polish President Lech Aleksander Kaczyński where Russians were shooting at Polish security and the press at the crash site - the Russians at the scene confiscated cameras from the press and looting took place.
Another fact was, according to Bill Gertz, NATO codes were confiscated by the Russians.
While the Smolensk plane crash was labeled an "accident", the evidence of the video of the radar that was controlling the approach of the president's plane was never given to investigators.
The video would have proven if the plane was on the glide slope when the Russian ATC said it was. If it wasn't on the glide slope when ATC said it was, then culpability would be placed on the Kremlin.
At Smolensk, a Kremlin liaison was in the tower and speaking to Moscow while the president's plane was landing - the phone call was supposedly never intercepted even with a president's plane landing.
The same pattern of Kremlin involvement with the downing of MH17 is similar to Smolensk - first there were the intercepted phone calls between Moscow and the rebels in the field.
Here the exchange between the rebels in the field and Kremlin liaison shows the coordination of communication after the plane was shot down.
There was the mindset of the Kremlin liaison that spies (military) were on board that aircraft. It was a military target.
Of course after the crash, warning shots were fired at people trying to get to the crash site, as was at the Smolensk crash site, then the looting and search for the black boxes took place with the rebels confiscating the black boxes.
The crash scene had been tainted as had been done at Smolensk.
As for the BUK SA-11 in stand alone use, it has a very limited range acquisition and would need prior intelligence that an aircraft was en route.
In stand alone use the BUK system has the ability to pick up the transponder of the MH17 letting the shooter know that it was a civilian airline.
This was no mistake made by the rebels and the Kremlin. Transponder codes would have to be entered to quickly target the aircraft.
Lastly, many of the victims came from the Netherlands, the country where NATO has its headquarters.
Like the Smolensk crash where the NATO codes were confiscated, this downing of the MH17 was Putin's message to NATO.
Update: Bloomberg posted an article that tries to build case of mistaken identity.The plane's transponder was broken or maybe turned off? Far-fetched.
Also there is a piece of the fuselage that has been found - also examining floor of fuselage in second photo there is shrapnel damage.
Update II: in a previous mentioned article published in Bloomberg online, a suggestion was made that MH17 transponder may have not be on or was not working - the Russian military was following the MH17 transponder on its radar.
Screen shot of Russian radar showing MH17 transponder on.