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?

it is a combo power amp and popcorn popper!!!

just be sure to use canola or light olive oil... butter can affect the sound, roll off the treble
It is possible that the design is optimized for cooling, and that the slot pattern promotes airflow. Perhaps a resident *thermodynamicist can chime in?

* A real one, not one of our resident "know-it-alls".
Well, since it is common knowledge, and my experience, that equipment turned on for longer time sounds better, I am pretty sure that the temperature is behind it. Hence my train of thought, however flawed may be, that increasing the temperature slightly more might be beneficial.  It is hard for me to believe that engineers at Durob Audio, quite reputable outfit, would somehow missed the consequences of their design. Especially that their Primaluna line has so different approach. 
Just a food for thought.
jjss49 and ebm - thanks for very insightful responses.