This seems like a solved problem as well. Don't people use focus groups anymore? Or have an open feedback forum where people can submit feedback and use user ratings to see which issues are the most important to the most users.

Many companies already do have forums like this and they're filled with UI complaints having sometimes thousands of upvotes, but it's all for nothing because almost none of them actually use that feedback.

My bet is still on "UI design isn't a full-time job, it's project work, so UI designers have to keep moving things around to stay relevant in one company". As much as I don't like outsourcing, having a bunch of designers on your payroll with nothing to do most days but still needing to pass all the employee rating crap is bound to result in an unstable and never good enough UI.