The passports used that were stolen were stolen years ago, and were on Interpol records as such. That may - or more likely, may not - have some relevance. Terrorism is one of many equally remote possibilities; if terrorism, why a Malaysian aeroplane? Why no claim? In general, terrorism events have the purpose of publicising the terrorists' cause, and the choice of terror act has some logical link to that cause. There are disgruntled people in Malaysia, but there are anywhere. Disgruntled enough to bring down an aeroplane? Perhaps it's related to the recent atrocities in China - but then why not a Chinese aircraft?
There have been instances of aircraft disintegrating in flight without terrorism being involved - the two most recently famous being the TWA Boeing 747 in 1996 that exploded over the Atlantic near New York and the Air France A330 that crashed into the South Atlantic in 2009. It took four years to determine ( and then arguably not conclusively) the cause of the TWA accident, and three years to get the final report on AF447 (two years just to find the 'black boxes').
A question that will be prevalent in the investigators' minds will be why, in this age of interconnected everything, the datalinking between the aircraft and the ground wasn't fast, detailed, or robust enough to show what happened, even if they could not show why. There should be no need for 'black boxes' these days. All modern aircraft are capable of datalinking their flight and system details to their operators to some degree - that's how flight status websites work, using the public part of that data.
So, yes, this is odd. And there should be much more known about it than there is. However, even when the black boxes are found and the information therein is decoded, it'll likely be quite some time before a comprehensive report is available.
