From what I read, it's a case of "can't do it the right way originally because of patents/legal/whatever; can't change it to the right way ever since because then every airbus pilot would need to requalify, every book rewritten, etc ...". Sounds like a terrible case of rotten legacy support.

A dual input alarm sounds when that happens.

The pilots should never both be trying to apply control inputs at once. There isn't really a good way of handling the situation where the pilots are not communicating and are trying to make conflicting control inputs.

Since I read that Popular Mechanics article, I think the exact same thing every time I board an Airbus plane.

Airbus has since updated its flight control feedback systems

Source for this?

I may be mistaken; I had thought I had read that Airbus had acted, but on checking up, I think not in ways which would make my brief implication useful.