You never actually achieve that speed in reality so bigger is better.
Not if you are sat in your living room and some twonk trips over a cable to your laptopMost the world is connected with wires. They are better, simpler and cheaper.
Just to add that wireless works for most but it wasn't working for streaming my HD media. 300mbps network with a good signal but it wanted to buffer every few mins. I got the 200mbps powerline and it's rock solid.
Wouldn't happen with a desktop
Same, wireless rarely cuts it for HD content.