Webhooks like yours will still be needed for a while (or programmable frameworks like Kyverno).

I'm not the biggest fan of mutating webhooks (vs validating ones), due to the fact that what you set is no longer what you see.

Now, its "cute" to be able to do it this way and the mutating webhook does solve a real problem by acting as a "virtualization layer", but that only really works if you want a write only system (which IMO somewhat defeats the point of kubernetes).

Now it could be that such a tool is valuable to motivate the need for this functionality to be actually be a configurable option within the container runtime, and without such a tool we wouldn't be able to really demonstrate the need.

I guess if you don't control the platform you are running on this is a way to do it in "userspace"