So, here we go again boys and girls!
Why is making it an option such a bad idea / touchy subject?
IMHO, it is a very good idea. As for the touchy – Doof explains it very well.
The answer amounts to "option overload". The stated goal is to have Theater View completely usable with a remote that only provides 5 keys (4 arrows and an enter key), and to have it work intuitively, without confusing new users or forcing them to dig into an increasingly arcane Options dialog panel.
If it can be said working right now as above then an option under Options/Theatre View (accessible in Normal View) would not change this “right” way unless the user wants to change it.
I also believe that sometimes you want to Play (selected items), sometimes to Show (drill down), sometimes to Add (to playing queue). Sometimes you want menu, sometimes you don’t. People that I observe and I want most often to drill down when on a folder/group and play when on a single item. This is the way that many other tools work. Sometimes I do use the other actions too.
One solution that has been proposed above is to have the menu popup when you press and hold Enter key (on the keyboard or on remote). This is doable as most remotes and keyboards differentiate between key down and key up events. Therefore an application can measure the time between down and up and make a decision based on that. This need not to be that simple to program as it sounds.
Another solution, perhaps more satisfactory from a generalist point of view would be to have a number of actions such as Play, Shuffle, Show, Menu etc. and then give an advanced user a way to assign what key/button should perform which actions in a specified context. Default could be “show Menu on Enter” which corresponds to current behavior. Another user could say “On Enter key: Show when on a group of files, Play when on a single file; On Menu key: display Menu” This could be combined with “hold Enter” so that holding Enter could be mapped to menu. This is implemented partly in MC right now but not all interesting actions are available and not all keys/buttons/contexts can be specified. In particular, Theatre View actions and MCE remote are not as well supported as one would wish.
Perhaps this is something we will get in MC Version 13.