you may not need to worry too much about well-built wheels breaking on
those rough roads and trails, but if you're traveling in developing countries,
you're likely to be using public transportation occasionally. baggage handling
is also developing.
if you're not there to supervise the loading, your bike could be laid down flat
with a couple sacks of cement and a bag of live chickens stacked on top, or
squeezed/forced into spots not large enough or unsuitable. wheels and
derailleurs particularly vulnerable.