Space is an important commodity there. Unfortunately, they've had a lot more room become available on the east coast in the last year.
According to the melon site, they made them squares to save space, but it's gotta be very labor intensive and time consuming to take a baby melon and shove it into a box to finish up its growing when you could just leave it alone to grow on the ground.
You know the real test isn't whether it fits in your fridge, but what do the black folk think of them?
I seriously recommend holding off reading book 2 and watching the seasons first. I just think it would be more exciting that way.