Unmanaged PoE is fine for a flat network
If the goal is only to power a few devices and plug them into the same LAN, unmanaged PoE is simpler and cheaper.
Managed PoE helps with isolation
Cameras, guest Wi-Fi, smart-home devices, and access points often deserve VLAN or traffic controls. Easy Smart switches can be enough for basic segmentation.
Monitoring can save troubleshooting time
Port status, PoE draw, link speed, and error counters help diagnose a camera that drops offline or an AP that negotiates the wrong speed.
Complexity has a cost
Do not buy a managed switch if nobody will maintain VLANs, firmware, passwords, backups, or documentation.