How does systemd help with this? The networkd component is still underdeveloped and unfinished, and meant for container setups, primarily.

networkd is still under development but if you're running a version of systemd that has it, it's already very nice so long as you don't need wifi. Right now I'd recommend it over NetworkManager for users who don't mind config files instead of using a GUI if they have access to it. It just works and it's automatically triggered by udev right when the hardware appears on the bus and sets everything up without the pile of shell scripts that is the status quo right now.

It pretty painless in my experience but i guess your millage may very on that.