thought I'd check this one with python-dev before marking it as "won't fix". I cannot see any reason why anyone would even attempt to deepcopy match objects...
Likely just because they're part of other objects, like bound to instance attributes, or members of lists. No matter how deep they're buried, someone trying to deepcopy a container will eventually need to deepcopy them too.
(cannot see any reason why anyone would use deepcopy for anything, but that's another story)
It's a std way to get a clone of an object, and when you don't want mutations of the clone to have any effect on the original (or vice versa). Perhaps if I call it the Clone Pattern, people will assume that makes it a good thing and cut that part of the debate mercifully short <wink>.
It's *nice* to supply a deepcopy operation whenever it's doable with reasonable effort. I agree you're not required to in this case -- but it would still be "nice", if that's feasible.