I sympathise with the OP. I am not shocked, however. I don't know if the OP's "personal items" were of high value but it's lucky that they were not taken. I'm always aware that on longhaul flights overnight others may move around the premium cabins on an aircraft so I ensure that my valuables (passport, expensive jewellery) are in my pockets. I think the extensive thefts from Japanese passengers in business class on one flight about a year ago were only reported because so many were robbed. Similar thefts have occurred on US airlines.