I'm perfectly content with the current ability of the Oasis 3, and other models too of course, to render and format books. In the early days when the eInk screens were very low resolution and had dark backgrounds and Kindles had almost no formatting options, then I was not content at all, and basically had to spend a lot of time deDRMing and modifying books to make them easier to read on those early eInk readers. I actually preferred the Sony readers in those days. But today Kindles have much better text formatting options and way better eInk screens, so now I can simply read and not worry about having to modify books.
I understand the urge to hack stuff, after all I grew up in the era when hackers like the Woz were starting to build home computers and when you had to program your own apps because the home PC software market had not yet taken hold. I no longer have to hack in order to modify books and Kindles so I can read without getting a headache. So today I’ve no desire to spend time JBing anything, and I really don’t need to any more. Heck, in old age I’m not even interested in spending time to use calibre. I can easily find my books on the Amazon Cloud, and thankfully I still have a great memory that probably does better categorizing and ordering my library than calibre anyway. In this stage of life, quickly approaching the Winter thereof, it seems rather wasteful to spend a lot of time making minor and superficial tweaks that don't offer much improvement. Heck, back in the mid-1990s I used to read books on a Palm Pilot which had only a 160px x 160px screen! So I can darn sure make do with what Kindle technology has to offer right out of the box today. Of course in the 1990s my eyes were still just middle-aged!