You have to understand that initially there was no plan to include an English cockpit at all, it was created by a tester as a mod and incorporated into the Sim long after the English manual had been completed. So the English labels are actually a bonus for those who want to trade realism for convenience. ;) And don't underestimate the work required to make the screenshots. I took those for the German GUI manual (which has much less screens than the flight manual), it's not just making the pics what takes time, but also "arranging the scene" before taking a pic and the editing (cutting, resizing, adjusting info pointers etc.) afterwards.
Personally I don't understand what all the fuss is about, I mean you can easily identify each switch etc. by its location, what do you need labels for?