It's disappointing they stay below the B5/10" size range, and can't step up to a A4/13" which allows full right/left page display or magazine pages at 1:1 size display.
It's particularly frustrating for manga, which Amazon sells plenty, as it's common to have a full 2 page scene during the most intense parts of the story.
Same of course for many research PDFs with graphs and schemas that are just so much more legible near the A4 size.
That was my main use case for the iPad Pro, which can now be covered by the air as well. The Surface Pro line is also around 13". I think there's really no reason to shy away from the full A4 size, especially when people are ready to pay for the screen real estate.