weakref and circular references: should I really care?

While Python has a garbage collector pretty much whenever circular references are touched upon it is advised to use weak references or otherwise break the cycle. But should we really care? I'd like not to, it seem like something the platfrom (python vm) should just provide for me. Are all those mentions really just for the cases where you can't (or don't want to, e.g. embedded) use the normal garbage collector?

Update

By some strange brain failure I seemed to have written "imports" rather then "references" in the title originally. They are obviously a bad thing.