With a FreeBSD or Linux machine, even step one requires considerable thought. Are there web UI packages that I can use? Which one do I pick? Where do I install it from? How do I ensure that it runs on boot? Do I have to mess with the network configuration to ensure that http://mynas.local is accessible? How do I configure SMB? What's the deal with security updates? And so on, dozens of times over.
It's great if you're already in the depths of sysadmindom and know what you're doing, but man, I just want to put my files on some LAN drives and call it a day.