I actually understand more bezel for landscape use. It makes sense. You're holding it differently than you would in portrait and the weight of the device (even if it's light) acts differently when held in portrait vs landscape. In portrait, you can hold the device "from behind" so to speak, with your fingers around the sides. With landscape, you can't do that and have to hold it from only one side (top or bottom) so you'd need more space for better grip.
However, there is still way too much bezel. More than it's required to hold it in landscape comfortably.
I have to believe ASUS simply couldn't fit the dual cameras and dual speakers without increasing the bezel.
BTW, the off-center front facing camera is to compensate for use in landscape mode, for whoever was concerned about that in an earlier post.