maybe the ratio is close enough to a square that it's offering them that way? or maybe its a new thing. i think i mentioned having that as an option in a suggestion once, though i'd like custom sizes personally. - or round.
If you click on Craig's link, then go to Art Prices, you'll see the square crops are more expensive, but when you click on the square, the image does not change as it should to show the different dimension.
With landscapes it wouldn't make that much difference to me. If the customer wants to buy something chopped off its up to them. But certain images it wouldn't work as something that contributes to the composition may be chopped off.
optical illusion the box is square...there not square they default to a square format that is why horizontal/vertical images look goofy...pick any persons gallery if you look at them under " images" they will show normal horizontal/vertical or square but press " gallery" they default to square .