"I don't understand why they are marketing it."

Simples - because they sell more than any other shape. It's Marketing Common Sense - people want them and are prepared to buy them, so make them and sell them.

It's horses for courses where guitar shapes and sizes are concerned, not a 'one-size-fits-all' scenario.

For anyone looking for a do-anything-go-anywhere-workhorse kind of guitar, they can do a lot worse than buy a Dread.

BTW, I have two guitars, neither of them is a Dread, so I have no axe to grind here (pun intended). :-)