Do I need Power over Ethernet (PoE) in the home?

No, of course not -- there are numerous workable alternatives. This is like asking "do I have to take a taxi to get downtown?"  Works for some, not for all, and certainly not required.

If you don't know if you need it then no. PoE is used to power some devices like CCTV using ethernet. Connecting a non-PoE device like a computer will kill the motherboard.

I have a POE CCTV system - this avoids having separate power cables to the CCTV cameras. Otherwise for the normal domestic user it probably isn't needed

For most people no.  

That being said.... I set up networks and smart home equipment in new homes.  In the homes I work on we use a PoE capable switch to form the network connection and provide power to Wi-Fi access points that are installed on the ceiling.  Some homes have one access point, some have more.  The advantage to PoE is that you don't have plug your PoE powered device into a mains power source in addition to the Ethernet cable. If you need it or not will depend on what "things" you are connecting to the network. Devices that use PoE include IP telephones, Wi-Fi access points and surveillance cameras.  Any "big device" that has a power cord, like a desktop PC or printer or TV or game console isn't going to use PoE.It doesn't hurt you to have an Ethernet switch capable of supporting PoE.  PoE is something the switch and the device negotiate when you connect the Ethernet cable.  If the device doesn't recognize/respond to the PoE signal from the switch, the switch won't turn on the power to it.  

An alternative to having a PoE capable Ethernet switch is to use devices known as PoE injectors to power a device that uses PoE.  PoE injectors are small devices that plug into the mains power source and have two Ethernet ports on them.  Generally you install them close to the device side (vs switch side) and they provide the PoE element for a switch that doesn't support it. 

Networking equipment can be installed in places without power supplies. But there aren't that many POE things you might need it.

Access Point placement can be easier. Wired web cams. But you need POE equipment and POE switches or injectors.

We use it for Wifi access points because the ones we have are meant to be installed from the ceiling or on a wall.

Need? No. ..................

no