Hey, Jens, 2 - 5 km walk and 100 to 300 m ascent is just a short hands-in-pockets stroll! Some of the hills in GM demand a 35 km round walk and an ascent of about a km!
Seriously, though, given the rules of SOTA which were established right at the beginning and remain largely unchanged to this day, the MT were faced with the choice of deleting non-P100 hills in Germany or changing the rules for the rest of the world. What would you have done if you were on the MT?
yes, you are right there are P100s which are reachable by car and good streets. But you must admit that they were summits which are on TOP50 and on the list which I could not even detect a peak (if you want an example Erbeskopf P100 DM/RP-158 one of the highest hills in RP - indeed reachable by car - and nearby Springenkopf DM/RP-161 no real peak. But there will be a lot of new ones really difficult to get on. In my region(Westerwald) we lost a lot. But I am in favour of P100 because you can immediately see that there is a mountain and not only a named hill.
Believe me there are a lot of new ones to detect(at least in RP and NW).