[Fire Q&A, Help & Troubleshooting] Nazo:
Actually, the OS being outdated is an argument for cracking the thing open and getting LineageOS or something AOSP on there. Quite frankly FireOS sucks and anyone who deals with the Fire tablets has had at least one annoyance in dealing with it (probably a heck of a lot more.) Heck, I set my grandmother up with one because she recently broke a really really nice Sony Z2 tablet (10", great quality screen, and officially unlockable bootloader with CyanogenMod available and probably LineageOS, but I never got around to it since she needed a specialized setup.) She's having troubles with the fact that many shortcuts that are standard on pretty much every single other Android distribution are hard to get to and require more steps to remember. (But, hey, $50 at a time when money is an issue for all of us is hard to beat.) For me it's pretty much everything people here are running into. Heck, you can use the launcher hijack thing to try to make it go to another launcher such as Nova, but their built in awful one still takes back over more often than not, so even just getting to my apps organized my way instead of their not so organized way is a lot harder. And lack of root means I can't even use Greenify. I'm still a little shocked how awful this thing's battery life is. I'm using it as something to carry around instead of my 2013 Nexus 7 (still 10x better than this thing at least) because I drop that thing way too much and worry someone would steal it (it still looks better than most tablets today!) and finding my Nexus 7 would go down maybe 5-10% in a day of normal use (mostly reading) whereas this thing goes down about 30-40% a day through the exact same use. Even a temproot with Greenify would make me a lot happier.

And I wouldn't say the Fire 8 existing explains anything. For one, it's more expensive. Not sure why you skipped over that, but $50 is more expensive than $30. Yet it doesn't really offer anything over the Fire 7. It's heavier and yet the screen isn't really that significantly bigger. It actually kind of ends up at a bad point where it's less able to fit in various things and more unwieldy, yet not really large enough to be as beneficial as a large screen tablet can be. Though I will admit it's not badly so (and in all fairness the Fire 7 is pretty unwieldy too. Especially it's shockingly thick. But I'm coming from that 2013 Nexus 7 which is still, today, one of the thinner tablets in this range. Just less so.) Besides, the two are very similar in a lot of ways and while they do have their differences that could affect this, an exploit for one may well actually apply to the other. Really the biggest difference lies more in the starting software. The 7 was slightly less locked down in older ROMs and the bootloader hasn't blacklisted them but the 8 is just a bit newer and it's more like it just started at a later software revision than that it's even truly all that different in that respect. (I'm sure there are differences here and there that can affect things, but for the most part they're pretty similar and I wouldn't split them up necessarily.)

More likely the real problem is just how hard Amazon is working to try to keep it from being "hacked." They've had a number of generations to perfect this and at this point it's much like a modern console in that they're locking things down more and more and learning how to keep it locked down. Realistically speaking, Amazon must surely lose a fair bit of money on the actual hardware given the price. There is literally no way they can sell these tablets at these prices and not lose money if you look only at the actual cost of production and the sale price. However they obviously make a fair bit via other means. Advertising being the most obvious, but also the way they've integrated their own services so much into there helps encourage people to buy through them and other stuff like this. All of this is pretty much the first to go on a "hacked" tablet. Just changing your launcher alone -- even if you don't do major ad blocking -- probably hurts their profit margins. Or so they assume. (It's actually more complicated than this. The sorts of people who would block their ads and change the launcher or even the entire OS are probably not that likely to click through or whatever anyway, so this means it wouldn't necessarily affect revenue if they had a hack, but you'll never convince them of this. Worse, if the process is too easy then everyone does it and if it's still moderately easy then people snatch up a bunch of them and give them to friends and family. If this happens on a large enough scale the actual cost of production versus the sale price starts to really hurt. They need that revenue on ads and market usage.) In the end it's not so different from the way consoles are so very locked down and require a lot of time and effort to exploit. The main difference is that the Android community is generally much more spread out whereas console communities get to focus a lot more. (Numerous very different devices versus very few.) There are numerous far nicer devices to be working with and these just have the advantage of being so cheap. (Plus it's a bit of a moving target since they make a new one every year or so.)

All that said, moving target or no, it's a good price and something cheap and easy to pick up and mess with, so there's still at least some small hope someone might eventually find something. Unfortunately, we may only have until the next hardware revision before people lose interest.

PS. 64-bit means nothing with current day Android usage. Oh sure, some are throwing more and more RAM at the bloatware messes they make *coughsamsungcough* and technically 64-bit does address amounts > 4GiB better (via methods such as PAE you can do more on 32-bit systems -- up to something like 64GB being fairly viable as I recall -- but obviously 64-bit does it a bit better since it's direct) but in real life usage if your tablet is truly using that much RAM you're doing it wrong and have a mess that needs to be cleaned up. It's like if your garbage is piling up in your house you need to start taking it out every week, not just get more garbage cans to pile it all in and take it out once a month. Whether you throw more RAM at it or not, the bloatware is still bloatware and going to 64-bit and throwing lots of RAM at it won't really help that (or even make any real dent in it.) In fact, almost nothing can truly utilize it and most of it is just filesystem buffers and the like -- which is to say mostly stuff gets thrown at it just because it's there but it isn't truly being utilized. In the case of the garbage example, you can "buffer" by having more cans, but they take up more room until you start tripping on them and you're going to get a bit of a smell keeping your kitchen garbage for a month at a time. The main point of the switch to 64-bit in Android is a future proofing as the general designs in software and hardware do need to eventually move that direction rather than that it's specifically truly necessary right now and it's better to go ahead and smoothly transition instead of waiting until the last minute and creating Y2K bug style situations.