<<Can anybody suggest why so many recent television commercials are
being shot and shown in a letterbox format?>>
 
Probably because it mimics the form of a much more "prestigious" art form
than television. Of course, that perception is sometimes unjustified, but
even tv types aspire to the more "traditional" medium of television. This is
allied with Marshall McLuhan's notion that the current dominant medium is
always seen as "less prestigious" than the previous dominant form (the
"rear-view mirror" notion of media).
 
It also intrigues me why so many video buffs insist on a "letterbox" format
of their favorite film. Not all films benefit from an ersatz "letterboxing".
It is primarily the anamorphic films which require it, but I constantly read
requests for "letterboxed" versions of "Citizen Kane" or other "flat" films.
I think this is also a misplaced idea of one form being inherently superior
to another. It's also evidence of a  culture-wide retreat into slogans rather
than serious inquiry into the actual facts.
 
Gene Stavis, School of Visual Arts - NYC