ECC is about long term stability and data integrity. For a router, meh, the network protocols will deal with any flips. For a file server or database it's better if those random bit flips don't happen to critical data.
AMD based systems can sometimes be forced to use ECC mode even if the BOIS doesn't support it.
ECC is more important in systems with very large ram footprints because there's that much larger of a memory footprint area for cosmic rays to corrupt. If you've got one-two sticks of ram, and you're not running vital business data, meh, it's not required.
I really like ECC. But I'm not really willing to pay a significant premium for it.
I run companion systems to production out of my house, mostly development lanes comparable to production deployments. If they're down, it's really not mission critical. I also run my home security/surveillance systems. The other significant systems are those related to my children's computer lab.