>If you are a Firefox user, you don’t have to do anything to benefit from this security advancement.

The epitome of corporate speak: "we're taking away a feature of this software. You're welcome."

I expect that kind of talk from Google; hearing it from Mozilla makes me a little sad.

but why?

maintaining features is cost

Perhaps one day we can have a programming language that allows us to write software that doesn't rot or corrode.

We can start by writing software that doesn't have any features at all, and save ourselves the trouble of removing them later. /s