The thing is, I did have encryption keys set up. The problem was that Element would repeatedly forget the very encryption keys passed by the other user, and would then have to request the keys again. Any historical message history would be permanently encrypted forever, and wouldn’t decrypt with the new view key.
After this happened about 4 times, I stopped using it, because it was impossible to maintain conversations for longer than 1-2 weeks before they’d inevitably be lost, and I’d then have to spend about an hour waiting for Element to receive the new encryption keys from the people I was contacting, even when they were already actively online.
I have no clue what was causing it, but it happened on multiple accounts, on multiple devices, all the time, and there was no conceivable fix. I’m not sure if this is fixed now, but I haven’t had a good reason to go back, especially with other encrypted messaging options out there.
I suppose they could, but even cold storage has a cost, and with the scale Discord’s operating at, they definitely have many terabytes of data that comes into the CDN every day, and that cost adds up if you’re storing it permanently.
I also think the vast majority of users would prefer being able to upload much higher resolution images and videos, to being able to see the image they sent with their messages a year ago. I don’t often go back through my messages, but I often find myself compressing or lowering the quality of the things I’m uploading on a regular basis.
They could also do the other common sense thing, which is to, on the client side of things, compress images and videos before sending them.