For most people a wireless network at home is enough. Basic web surfing and mail checking is all they do. Maybe even watch a little bit of youtube occasionally. However, for others, you have much higher demands on a home network, then setting up a wired LAN is the only way to go. The faster wireless networks are still not cheap enough and not all devices support these standards. Here are just a couple of instances of what is possible if you have a wired LAN at home:
Speed
A wired network can give you a gigabit between each node in the network. With gigabit ethernet becoming a reality for many, a standard wireless network will not be able to handle that kind of throughput to make it useful. Eventually when 4k video becomes standard, you will need a much faster network. Mostly due to the fact that when one heavy streams takes of over a wireless network, it effectively becomes useless for anyone else. A wired network will have the kind of bandwidth to allow multiple streams and surfing sessions at once.
Appliances and Storage
Another benefit of a LAN is that you can then connect your own server at home, possibly for a home media server. In addition there are appliances like network attached storage for multiple people to store their files at home. Even home automation hubs have network ports and a home network means you don’t have to keep it next to your router and can be placed anywhere.