Long-stay residents want a TV. So if there is only one common area and the hostel wants to appeal to long-stays, they give a TV pride of place. And it's always on, so sociability is greatly reduced.
The hostels that people rave about are the ones where there is no TV, or where the TV is not dominant. You rarely see reviews like: "The hostel is great, I could watch sport/movies all evening!'. (Except reviews written by or on behalf of the staff, identifiable by things such as: only positive things are mentioned; and ALL positive things are mentioned.)