I have a Fire 7” and a Fire 8”, and I can do the same as you with enlarging the pictures, but I still prefer using my 10.5 iPad when I am reading something where i do want to enlarge something enough to see fine details. Also, since I save pictures on the iPad, if there is a picture of chart of some kind that is part of the book, and I want to save that picture, I take a screenshot from the iPad and then have the picture saved to my photo stream. I don’t save anything like that in the Fire tablet, so even though I could take a screenshot that way, it wouldn’t be helpful to me. Sometimes, I just want to save a page in a book that is not a picture, but says something I might want to share with my family, or here on the forum. With the iPad, I can take a screenshot of that page and then share that with people.