Not sure why they did the transition like that.
Because that's exactly what the original class 3 allowed you to drive. Imagine what would have happened if they told everyone with a driving license at that point that it's now only viable for 3,5t vehicles without a trailer and they need to make a new license to keep driving their transporters, small trucks or using their trailers.
Realistisch betrachtet? Der Zug ist längst abgefahren und du bekommst es einfach erst sehr viel später mit, wenn der Mist aus den geschlossenen Communities in die wirklich Welt schwappt...