Mystere tube cage

Just wondering while listening to my Mystere IA11, which I enjoy quite a lot, and looking at the tube “cage” which in itself is a steel box with just a few openings not really providing much ventilation. Was it the intention of the designer to keep tubes hotter than their line of Primaluna with “real” tube cages like probably all other tube based products? Or it is just esthetics and the decreased cooling of tubes does not matter? Have that questions in back of my mind for as long as I have owned the amplifier. What say you?