Its a shame that the towers arnt properly used. There isnt even any proper signs directing you into them. I have seen some old photos of the towers in the 80s when there was a big sign above the enterance (near Hex exit) saying Towers and information. Now you just go through what seems like a firedoor and a emergency staircase.
There should be a proper enterance and signs and information in each room, Telling you information about the room, old photos, etc. Some proper history about the Towers and what its been used for over the years.
There are plenty of people who go to Alton Towers who dont go on the rides, such as parents/grand parents who may wonder round the towers, but dont have a clue about the history or anything.
As for tours, im not sure there would be enough demand for it, and it could end up with a tour guide showing two people round especially on quite or wet days.