Interesting observation, Alain. I tend to agree. I know that Des never weathers his models, he likes them factory fresh, but weathering in WWI modelling is definitely far less prevalent than, for instance, WWII modelling.
Personally, I prefer a weathered model over a factory finish, only because it adds a degree of realism and more accurately reflects how the planes looked most of the time.
Perhaps WWI planes, like their pilots, did not live long enough to get n properly weathered? It's certainly a very defendable position to adopt as a modeler.
However, this takes nothing away from Des's skills, which are absolutely outstanding.