Um...I believe originally my idea was that there would be a deeper examine command to show the long_desc.
There are currently three ways an object may be shown in the room: using @show_in_look, in a list (blah and blah are here), or not at all (@show_in_look set to "" or false). This is pretty hacky, I guess.
Looking over the code, it does not look like long_desc or short_desc are really tied to much in particular. ADESC uses short_desc but LOOK shows long_desc.
At the moment, long_desc falls back on short_desc if long_desc is not defined.
So, I guess the conclusion is do whatever you'd like, it isn't going to break anything major that I can think of
