Couple things we said if we are ever looking for the reasoning in the future:
We should always copy the thing the user can see, so if we see name-of-thing we should copy name-of-thing not name-of-thing.namespace.
Because we wrap the "name of the thing" in a link, its slightly more difficult to copy by just selecting and hitting ctrl-c, therefore there is a good reason to use a copy button on these things rather than just assume the user can copy these normally.
What happened?
In the Dataplane proxies list for example it's missing.
Let's go over all our lists and make sure we have copy buttons.