Could be that it provides more flexiblity to the airframe. Or that too much horizontal stabilizer would limit pitch ability. Other aerodynamic effects may be in play as well, since it's carrying the payload in the center.
Single engine out isn't probably much of a concern as there are two redundant engines per side.
Single engine out isn't probably much of a concern as there are two redundant engines per side.
I'm just speculating though.