I don't know, but I guess due to the increase in popularity with broadband, and people's desire for lack of wires as well as people who are constantly on the go and want something simple that works. People are more dependent on the internet for information and other things like making money (example is here). Plus, internet is built into everything these days... Photo frames, SD cards, Phones, Laptops, Media Players and more! and provides greater convenience, such as media players can download music directly from a music store, or being able to collaborate with business partners via your laptop at an airport.
Because of the convenience. People who are always on the move have to depend on wifi because it is high speed internet untethered
I have a wireless router @home for 1 Month and I prefer it so much more than the wired connection. I can move all around without switching cables and the speed is good 2+ MB/s. with torrent files.