A previous company I worked at had both a huge selection of wine and a kegerator in the office. I don't think the novelty of having a glass of beer or wine easily accessible at the end of the day ever really wore off, especially since the beer and wine selection constantly rotated.
At least in our case it seemed to be more of a social experience for different groups of the company to relax and talk to each other, as the company was maybe 25% devs, not everyone got to regularly work with others from other departments. Sure we could have all gone out to a bar but most bars nearby were always packed with the afterwork crowd making just walking around talking to each other a huge chore (think near the front of a concert style packed).
At least in our case it seemed to be more of a social experience for different groups of the company to relax and talk to each other, as the company was maybe 25% devs, not everyone got to regularly work with others from other departments. Sure we could have all gone out to a bar but most bars nearby were always packed with the afterwork crowd making just walking around talking to each other a huge chore (think near the front of a concert style packed).