Another reason (or two) for the Asko drop-down outer door, is for use as a shelf when loading/unloading the machine. Another reputedly has to do with styling. In some households where these machines may be installed (such as in a kitchen, or other high-traffic area), the outer door helps create a "clean" or "flush" appearance. The older BOL Asko's (like my W600) don't have the outer door. I asked the guy who worked at the Asko dealer where I bought my machines about the outer door, and he opined that if the washer & dryer were to be installed in a "concelaed" location (like a basement; a closet, or an alcove where there are, say, folding doors)then the models with the outer door were all but pointless.
As of a few years ago, Asko stopped offering the "outer-door-less" models, as they otherwise were identical to those that had them.