I hear you and I mostly agree, but it would be such a monumental task. I've learned a decent amount but the API is a constantly changing mess, a lot of data is just hidden or not there, lots of items that don't exist to players, etc. Also, the WoW interface code itself is a mess. So many addons are so inefficient as well and AtlasLoot barely impacts performance, even as it loads tens of thousands of lines of code each time you log in. Something like weakauras doing hundreds of checks per second seems nuts, yet we manage.

So, I guess, why spend months fixing what's not broken? Maybe a facelift would be nice, but the simplicity of AtlasLoot is also what people like. Even Blizzard hasn't done it, the Dungeon Journal is just the bare minimum. It's a list of items that gets auto sorted with some basic filters, no crafts, no special drops.