Miele dryers have long been a tough sell
Besides the voltage requirement they are just seen as too "small" by many Americans.
Providing one has the space you can get a full sized American dry that runs on same 220v power for far less money. Then you had the fact not many liked condenser dryers, which is all Miele sells now in USA for several years having discontinued vented versions.
Arrival of the 3XXX series and their 120v voltage as stolen much of the thunder (and there wasn't much)for older Miele washers that need 120v/220v connections.
We can debate the build and whatever quality of new machines versus old until cows come home; but the overwhelming reason for poor Miele washer sales in past was their electrical requirements.
One suspects far more 19XX and 12XX series washers would have been "saved" if they could be run on 120v or even straight 220v by using a step-up converter/transformer.