It's not tested, and sure enough, a glance at the code suggests that `case` and `switch` will evaluate their first argument once for every clause, which is unlikely to be desirable. I say remove it, but if anybody wants to fix and test and re-add `case` (and change it to a square-bracket syntax like `cond`), be my guest.
I don't see why you'd put this in the standard library. I guess it could be useful for when you're maintaining a library and you want to change the name of a function or macro but keep the old name around for a while so people's code doesn't break immediately. But that's a pretty limited purpose.
