I think it's to make you drink, as you can't talk to each other so you may as well just drink fast.
Porter house has live music, but it's very repetitive. Same guy almost every friday/sat night, and the first time you see him he's good, after that same set, same songs, same jokes.
Also I think that as we get older and see our friends less regularly we tend to want to catch up rather than drink and dance. Thats my experience anyway.
I'd rather go to a proper gig than a bar with live music though usually. Can depend on the mood I suppose.