If we had those dream-sharing machines from Inception, and they could operate over the internet to connect with, for instance, our Facebook friends, then we could get days of socialising done while we sleep. It would be like going to a party where the food is infinite and non-fattening, the booze is free and the consequences of your actions are only as permanent as a video game. The problems of sharing your subconscious with your friends, however, are too many to list.
Mokalus of Borg
PS - Also, sleeping with a needle in your arm every night might not appeal to people.
PPS - I would assume it actually works with some kind of head gear.