The reason they are not installed by default is they are moving the plugins to be hosted in Patch Storage. That way you can just download what you want in the future.
However in the same thread where they announced Modep 1.12 there is a post on how to install all the previous plugins locally:
sudo apt install modep-lv2-*
sudo cp -r /usr/modep/lv2/* /var/modep/lv2
sudo chown -R modep:modep /var/modep/lv2
sudo chmod -R 775 /var/modep/lv2