Working canopies, and wings that fold for carrier planes would be cool.
Yes, it is totally useless as a gameplay mechanism

, but for immersion, it'd rock.
When canopies are open, maybe the range of the headmovements can be increased... it'd be cool to look on the side of the plane with the head sticking out during taxing.. also, cruising around in open canopies with the wind in your ears..(maybe larger wind sound when canopy open?).. then when about to engage, everybody closes their canopy.. hehe, that'd be cool..Seeing planes neatly lined up on the runway with caopies open.. and etc etc...
A small feature, but I'd say worth the effort!