No one outside of MikroTik would know for sure. But given the number of other threads that turn up if you search for 1072 RAM or crash or instability, it sure seems like poor manufacturing yields and quality assurance. Either that or they “test” fine after assembly, but something isn’t quite right & a solder joint or board trace or something gets broken during transit/shipment? Who knows…
http://forum.mikrotik.com/t/ccr1072-1g-8s-memory/108594/1
http://forum.mikrotik.com/t/mikrotik-ccr1072-new-with-4gb-of-ram-less/111973/1
http://forum.mikrotik.com/t/ccr1072-with-only-8gb-ram/127422/1