Why do most sandwich makers have a triangular shape? I've seen many hundreds of sandwich making machines in my life, and I noticed that in the vast majority of them, there is a diagonal protrusion that makes sandwiches come up in triangular shapes.



This makes no sense to me, for the following reasons:


Most packaged sliced bread is square, not triangular.
Most grilled sandwich recipes don't call for triangular shapes
You're forced to a triangular shape
Non-square bread slices are difficult to use with this triangular shape
The protrusion itself is much more difficult to clean than a simple flat iron.


Yet for some reason these sandwich makers are extremely common, to the point that flat makers are somewhat of a specialty item, therefore costing more.

I think I'm missing something here. Why do most sandwich makers use this triangular shape? What are the advantages of such a shape?
Typically with these sandwiches you have some cheese inside along with some other ingredients such as tomatoes that get quite hot (325° F sometimes).

From what I've seen, if you have a square only shape, you don't necessarily get a good seal, plus you get a massive pocket of hot lava.  The fat from the cheese or butter concentrates in the center, soaks and can break through the bread releasing hot lava on shirts, pants, open toes, etc.

Even if it doesn't suffer a total failure, you don't get a consistent sandwich.  Center will end up much soggier than the crusty rim and eating it can get difficult and messy.  Certainly no longer hors d'oeuvres stuff. 

The triangular shape essentially makes it bite-sized, so the stuffing doesn't run away after the first bite and becomes more manageable.

You can try using a grill or a panini press, but if you've noticed, those ones allow the oozing lava to escape and run away.  A calzone is similar to what you'd get, and a badly crafted calzone can be quite messy and again, not really an hors d'oeuvre.