The reason we've avoided registering "Cinnamon" as a desktop name is that it opens up issues with many upstream apps that currently OnlyShowIn=Gnome or Gnome;Unity or just Unity. The relationship Mint has with Gnome and Ubuntu isn't genial enough that we could get them to add Cinnamon to their desktop files, so we would have to distribute and maintain separate duplicate .desktop files just for Cinnamon for these upstream packages.

gsettings set org.gnome.mutter experimental-features "['scale-monitor-framebuffer']"

Systemd problems might not have mattered that much, except that GNOME has a similar attitude; they only care for a small subset of the Linux desktop users, and they have historically abandoned some ways of interacting the Desktop in the interest of supporting touchscreen devices and to try to attract less technically sophisticated users. If you don't fall in the demographic of what GNOME supports, you're sadly out of luck.

tox-prpl – Tox Protocol Plugin For Pidgin

I just tried it with your ppa but get “OTR is not supported on this account” when entering “/otr start” in a Jabber chat.