And my reaction was "That's awesome! I want to go and see a band and have them play the songs while the audience sings them! Why doesn't this already exist?"
Singing songs as a group is great fun, but most singing groups tend to focus on either choral/classical/religious songs. And they tend to be doing it so that they can perform.
You don't get sing-a-long-a-rock. And you bloody well should!
Original post on Dreamwidth - there are comments there.