I've visited the Amsterdam ArenA, the Nou Camp and Spurs stadium when visiting the cities unrelated to football to do their tours and see their museums, because I'm a football fan and I find it interesting. Not think Glasgow tourists has like minded folk?
I don't think anyone is expecting it to be queued out the door on a Tuesday morning, but it's not unreasonable to have multi purpose staff manning the store and being able to sell you a pre-pack sandwich and cup of tea upstairs along with your ticket into the museum, or selling matchday tickets. As things stand, that's 3 different locations requiring heated/powered/staffed to operate, that can/will be combined into 1.