TIR:

it's a fundamental aspect of Bitcoin's security model that node software does NOT automatically update. Auto-updates would create a single point of failure that could cause a malicious update to quickly spread to a supermajority of nodes on the network. As such, manual action must be taken by node operators to keep their node software up to date. This creates a point of friction and means that node operators must maintain some awareness of project development. 

 “Bitcoin is a constantly evolving adversarial environment: node operators should be aware that they should not just "set it and forget it" if they want to retain a strong security posture. Running a node to validate your funds against the rules of the network is the path to financial sovereignty, but it also means that you're taking on the same responsibilities as a server administrator!”